diff --git a/docs/05_content_nodes.md b/docs/05_content_nodes.md
index ee40b938..ddcb8db2 100644
--- a/docs/05_content_nodes.md
+++ b/docs/05_content_nodes.md
@@ -9,7 +9,7 @@ It is valid to have an anchor associated with a node even if it has no aliases.
 ## Scalar Values
 
 ```js
-class NodeBase {
+interface NodeBase {
   comment?: string        // a comment on or immediately after this
   commentBefore?: string  // a comment before this
   range?: [number, number, number]
@@ -19,16 +19,16 @@ class NodeBase {
       // included in their respective ranges.
   spaceBefore?: boolean
       // a blank line before this node and its commentBefore
-  tag?: string       // a fully qualified tag, if required
-  clone(): NodeBase  // a copy of this node
-  toJS(doc, context?): any // a plain JS representation of this node
+  tag?: string    // a fully qualified tag, if required
+  clone(): this   // a copy of this node
+  toJS(doc): any  // a plain JS representation of this node
 }
 ```
 
 For scalar values, the `tag` will not be set unless it was explicitly defined in the source document; this also applies for unsupported tags that have been resolved using a fallback tag (string, `YAMLMap`, or `YAMLSeq`).
 
 ```js
-class Scalar<T = unknown> extends NodeBase {
+class Scalar<T = unknown> implements NodeBase {
   anchor?: string  // an anchor associated with this node
   format?: 'BIN' | 'HEX' | 'OCT' | 'TIME' | undefined
       // By default (undefined), numbers use decimal notation.
@@ -54,12 +54,12 @@ class Pair {
   value: Node | null
 }
 
-class Collection extends NodeBase {
+class Collection implements NodeBase {
   anchor?: string  // an anchor associated with this node
   flow?: boolean   // use flow style when stringifying this
   schema?: Schema
   addIn(path: unknown[], value: unknown): void
-  clone(schema?: Schema): NodeBase  // a deep copy of this collection
+  clone(schema?: Schema): this  // a deep copy of this collection
   deleteIn(path: unknown[]): boolean
   getIn(path: unknown[], keepScalar?: boolean): unknown
   hasIn(path: unknown[]): boolean
@@ -140,7 +140,7 @@ Note that for `addIn` the path argument points to the collection rather than the
 
 <!-- prettier-ignore -->
 ```js
-class Alias extends NodeBase {
+class Alias implements NodeBase {
   source: string
   resolve(doc: Document): Scalar | YAMLMap | YAMLSeq | undefined
 }
diff --git a/src/compose/compose-collection.ts b/src/compose/compose-collection.ts
index 4162f81e..eb1e7f83 100644
--- a/src/compose/compose-collection.ts
+++ b/src/compose/compose-collection.ts
@@ -1,4 +1,5 @@
-import { NodeBase, type Node } from '../nodes/Node.ts'
+import { isNode } from '../nodes/identity.ts'
+import type { Node } from '../nodes/Node.ts'
 import { Scalar } from '../nodes/Scalar.ts'
 import { YAMLMap } from '../nodes/YAMLMap.ts'
 import { YAMLSeq } from '../nodes/YAMLSeq.ts'
@@ -135,7 +136,7 @@ export function composeCollection(
       ctx.options
     ) ?? coll
 
-  const node = res instanceof NodeBase ? (res as Node) : new Scalar(res)
+  const node = isNode(res) ? res : new Scalar(res)
   node.range = coll.range
   node.tag = tagName
   if (tag?.format) (node as Scalar).format = tag.format
diff --git a/src/compose/util-map-includes.ts b/src/compose/util-map-includes.ts
index 8d4e9b3a..f853de94 100644
--- a/src/compose/util-map-includes.ts
+++ b/src/compose/util-map-includes.ts
@@ -1,4 +1,4 @@
-import type { NodeBase } from '../nodes/Node.ts'
+import type { Node } from '../nodes/Node.ts'
 import type { Pair } from '../nodes/Pair.ts'
 import { Scalar } from '../nodes/Scalar.ts'
 import type { ComposeContext } from './compose-node.ts'
@@ -6,14 +6,14 @@ import type { ComposeContext } from './compose-node.ts'
 export function mapIncludes(
   ctx: ComposeContext,
   items: Pair[],
-  search: NodeBase
+  search: Node
 ): boolean {
   const { uniqueKeys } = ctx.options
   if (uniqueKeys === false) return false
   const isEqual =
     typeof uniqueKeys === 'function'
       ? uniqueKeys
-      : (a: NodeBase, b: NodeBase) =>
+      : (a: Node, b: Node) =>
           a === b ||
           (a instanceof Scalar && b instanceof Scalar && a.value === b.value)
   return items.some(pair => isEqual(pair.key, search))
diff --git a/src/doc/Document.ts b/src/doc/Document.ts
index d4b95610..de666740 100644
--- a/src/doc/Document.ts
+++ b/src/doc/Document.ts
@@ -2,7 +2,6 @@ import type { YAMLError, YAMLWarning } from '../errors.ts'
 import { Alias } from '../nodes/Alias.ts'
 import { Collection, type Primitive } from '../nodes/Collection.ts'
 import type { Node, NodeType, Range } from '../nodes/Node.ts'
-import type { NodeBase } from '../nodes/Node.ts'
 import type { Pair } from '../nodes/Pair.ts'
 import { Scalar } from '../nodes/Scalar.ts'
 import { ToJSContext } from '../nodes/toJS.ts'
@@ -226,13 +225,13 @@ export class Document<
     value: V,
     options: CreateNodeOptions = {}
   ): Pair<
-    K extends Primitive | NodeBase ? K : NodeBase,
-    V extends Primitive | NodeBase ? V : NodeBase
+    K extends Primitive | Node ? K : Node,
+    V extends Primitive | Node ? V : Node
   > {
     const nc = new NodeCreator(this, options)
     const pair = nc.createPair(key, value) as Pair<
-      K extends Primitive | NodeBase ? K : NodeBase,
-      V extends Primitive | NodeBase ? V : NodeBase
+      K extends Primitive | Node ? K : Node,
+      V extends Primitive | Node ? V : Node
     >
     nc.setAnchors()
     return pair
@@ -261,7 +260,7 @@ export class Document<
   /**
    * Returns item at `key`, or `undefined` if not found.
    */
-  get(key: any): Strict extends true ? NodeBase | Pair | undefined : any {
+  get(key: any): Strict extends true ? Node | Pair | undefined : any {
     return this.value instanceof Collection ? this.value.get(key) : undefined
   }
 
@@ -270,7 +269,7 @@ export class Document<
    */
   getIn(
     path: unknown[]
-  ): Strict extends true ? NodeBase | Pair | null | undefined : any {
+  ): Strict extends true ? Node | Pair | null | undefined : any {
     if (!path.length) return this.value
     return this.value instanceof Collection ? this.value.getIn(path) : undefined
   }
diff --git a/src/doc/NodeCreator.ts b/src/doc/NodeCreator.ts
index 57be20ee..7cf5035f 100644
--- a/src/doc/NodeCreator.ts
+++ b/src/doc/NodeCreator.ts
@@ -1,6 +1,7 @@
 import { Alias } from '../nodes/Alias.ts'
 import { Collection } from '../nodes/Collection.ts'
-import { type Node, NodeBase } from '../nodes/Node.ts'
+import { isNode } from '../nodes/identity.ts'
+import { type Node } from '../nodes/Node.ts'
 import { Pair } from '../nodes/Pair.ts'
 import { Scalar } from '../nodes/Scalar.ts'
 import type { YAMLMap } from '../nodes/YAMLMap.ts'
@@ -60,7 +61,7 @@ export class NodeCreator {
 
   create(value: unknown, tagName?: string): Node {
     if (value instanceof Document) value = value.value
-    if (value instanceof NodeBase) return value as Node
+    if (isNode(value)) return value
     if (value instanceof Pair) {
       const map = (this.schema.map.nodeClass! as typeof YAMLMap).from(
         this,
@@ -143,10 +144,10 @@ export class NodeCreator {
     return node
   }
 
-  createPair(key: unknown, value: unknown): Pair<NodeBase, NodeBase | null> {
+  createPair(key: unknown, value: unknown): Pair<Node, Node | null> {
     const k = this.create(key)
     const v = value == null ? null : this.create(value)
-    return new Pair<NodeBase, NodeBase | null>(k, v)
+    return new Pair<Node, Node | null>(k, v)
   }
 
   /**
diff --git a/src/doc/directives.ts b/src/doc/directives.ts
index aef96d06..38f84457 100644
--- a/src/doc/directives.ts
+++ b/src/doc/directives.ts
@@ -1,4 +1,3 @@
-import { NodeBase } from '../nodes/Node.ts'
 import { visit } from '../visit.ts'
 import type { Document } from './Document.ts'
 
@@ -182,8 +181,8 @@ export class Directives {
     let tagNames: string[]
     if (doc && tagEntries.length > 0) {
       const tags: Record<string, boolean> = {}
-      visit(doc.value, (_key, node) => {
-        if (node instanceof NodeBase && node.tag) tags[node.tag] = true
+      visit(doc.value, (_key, node: any) => {
+        if (node?.tag) tags[node.tag] = true
       })
       tagNames = Object.keys(tags)
     } else tagNames = []
diff --git a/src/index.ts b/src/index.ts
index 006750bd..ad063f60 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -15,7 +15,8 @@ export type { ErrorCode } from './errors.ts'
 export { YAMLError, YAMLParseError, YAMLWarning } from './errors.ts'
 
 export { Alias } from './nodes/Alias.ts'
-export type { Node, Range } from './nodes/Node.ts'
+export { isNode } from './nodes/identity.ts'
+export type { Node, NodeBase, Range } from './nodes/Node.ts'
 export { Pair } from './nodes/Pair.ts'
 export { Scalar } from './nodes/Scalar.ts'
 export { YAMLMap } from './nodes/YAMLMap.ts'
diff --git a/src/nodes/Alias.ts b/src/nodes/Alias.ts
index a38a341e..25922ab1 100644
--- a/src/nodes/Alias.ts
+++ b/src/nodes/Alias.ts
@@ -3,22 +3,40 @@ import type { Document, DocValue } from '../doc/Document.ts'
 import type { FlowScalar } from '../parse/cst.ts'
 import type { StringifyContext } from '../stringify/stringify.ts'
 import { visit } from '../visit.ts'
-import type { Node } from './Node.ts'
-import { NodeBase } from './Node.ts'
+import type { Node, NodeBase, Range } from './Node.ts'
 import { Pair } from './Pair.ts'
 import type { Scalar } from './Scalar.ts'
 import { ToJSContext } from './toJS.ts'
 import type { YAMLMap } from './YAMLMap.ts'
 import type { YAMLSeq } from './YAMLSeq.ts'
 
-export class Alias extends NodeBase {
+export class Alias implements NodeBase {
   source: string
 
   declare anchor?: never
+
+  /** A comment on or immediately after this node. */
+  declare comment?: string | null
+
+  /** A comment before this node. */
+  declare commentBefore?: string | null
+
+  /**
+   * The `[start, value-end, node-end]` character offsets for
+   * the part of the source parsed into this node (undefined if not parsed).
+   * The `value-end` and `node-end` positions are themselves not included in their respective ranges.
+   */
+  declare range?: Range | null
+
+  /** A blank line before this node and its commentBefore */
+  declare spaceBefore?: boolean
+
+  /** The CST token that was composed into this node.  */
   declare srcToken?: FlowScalar & { type: 'alias' }
 
+  declare tag?: never
+
   constructor(source: string) {
-    super()
     this.source = source
     Object.defineProperty(this, 'tag', {
       set() {
@@ -27,6 +45,16 @@ export class Alias extends NodeBase {
     })
   }
 
+  /** Create a copy of this node.  */
+  clone(): this {
+    const copy: this = Object.create(
+      Object.getPrototypeOf(this),
+      Object.getOwnPropertyDescriptors(this)
+    )
+    if (this.range) copy.range = [...this.range]
+    return copy
+  }
+
   /**
    * Resolve the value of this alias within `doc`, finding the last
    * instance of the `source` anchor before this node.
@@ -114,25 +142,24 @@ export class Alias extends NodeBase {
 
 function getAliasCount(
   doc: Document,
-  node: unknown,
+  node: Node | Pair | null,
   anchors: ToJSContext['anchors']
 ): number {
   if (node instanceof Alias) {
     const source = node.resolve(doc)
     const anchor = anchors && source && anchors.get(source)
     return anchor ? anchor.count * anchor.aliasCount : 0
-  } else if (node instanceof NodeBase && 'items' in node) {
-    const coll = node as YAMLMap | YAMLSeq
+  } else if (node instanceof Pair) {
+    const kc = getAliasCount(doc, node.key, anchors)
+    const vc = getAliasCount(doc, node.value, anchors)
+    return Math.max(kc, vc)
+  } else if (node && 'items' in node) {
     let count = 0
-    for (const item of coll.items) {
+    for (const item of node.items) {
       const c = getAliasCount(doc, item, anchors)
       if (c > count) count = c
     }
     return count
-  } else if (node instanceof Pair) {
-    const kc = getAliasCount(doc, node.key, anchors)
-    const vc = getAliasCount(doc, node.value, anchors)
-    return Math.max(kc, vc)
   }
   return 1
 }
diff --git a/src/nodes/Collection.ts b/src/nodes/Collection.ts
index a78a8edc..c60244b7 100644
--- a/src/nodes/Collection.ts
+++ b/src/nodes/Collection.ts
@@ -1,6 +1,7 @@
 import { NodeCreator } from '../doc/NodeCreator.ts'
+import type { Token } from '../parse/cst.ts'
 import type { Schema } from '../schema/Schema.ts'
-import { type Node, NodeBase } from './Node.ts'
+import type { Node, Range } from './Node.ts'
 import type { Pair } from './Pair.ts'
 import type { Scalar } from './Scalar.ts'
 
@@ -26,12 +27,12 @@ export function collectionFromPath(
   return new NodeCreator(schema, { aliasDuplicateObjects: false }).create(v)
 }
 
-export abstract class Collection extends NodeBase {
+export abstract class Collection {
   schema: Schema | undefined
 
-  declare items: (NodeBase | Pair)[]
+  declare items: (Node | Pair)[]
 
-  /** An optional anchor on this node. Used by alias nodes. */
+  /** An optional anchor on this collection. Used by alias nodes. */
   declare anchor?: string
 
   /**
@@ -40,8 +41,29 @@ export abstract class Collection extends NodeBase {
    */
   declare flow?: boolean
 
+  /** A comment on or immediately after this collection. */
+  declare comment?: string | null
+
+  /** A comment before this collection. */
+  declare commentBefore?: string | null
+
+  /**
+   * The `[start, value-end, node-end]` character offsets for
+   * the part of the source parsed into this collection (undefined if not parsed).
+   * The `value-end` and `node-end` positions are themselves not included in their respective ranges.
+   */
+  declare range?: Range | null
+
+  /** A blank line before this collection and its commentBefore */
+  declare spaceBefore?: boolean
+
+  /** The CST token that was composed into this collection.  */
+  declare srcToken?: Token
+
+  /** A fully qualified tag, if required */
+  declare tag?: string
+
   constructor(schema?: Schema) {
-    super()
     Object.defineProperty(this, 'schema', {
       value: schema,
       configurable: true,
@@ -55,14 +77,14 @@ export abstract class Collection extends NodeBase {
    *
    * @param schema - If defined, overwrites the original's schema
    */
-  clone(schema?: Schema): Collection {
-    const copy: Collection = Object.create(
+  clone(schema?: Schema): this {
+    const copy: this = Object.create(
       Object.getPrototypeOf(this),
       Object.getOwnPropertyDescriptors(this)
     )
     if (schema) copy.schema = schema
     copy.items = copy.items.map(it => it.clone(schema))
-    if (this.range) copy.range = this.range.slice() as NodeBase['range']
+    if (this.range) copy.range = [...this.range]
     return copy
   }
 
@@ -78,7 +100,7 @@ export abstract class Collection extends NodeBase {
   /**
    * Returns item at `key`, or `undefined` if not found.
    */
-  abstract get(key: unknown): NodeBase | Pair | undefined
+  abstract get(key: unknown): Node | Pair | undefined
 
   /**
    * Checks if the collection includes a value with the key `key`.
@@ -129,7 +151,7 @@ export abstract class Collection extends NodeBase {
   /**
    * Returns item at `key`, or `undefined` if not found.
    */
-  getIn(path: unknown[]): NodeBase | Pair | undefined {
+  getIn(path: unknown[]): Node | Pair | undefined {
     const [key, ...rest] = path
     const node = this.get(key)
     if (rest.length === 0) return node
diff --git a/src/nodes/Node.ts b/src/nodes/Node.ts
index bf7747fd..d656e111 100644
--- a/src/nodes/Node.ts
+++ b/src/nodes/Node.ts
@@ -1,11 +1,11 @@
 import type { Document, DocValue } from '../doc/Document.ts'
 import type { Token } from '../parse/cst.ts'
 import type { Schema } from '../schema/Schema.ts'
-import type { StringifyContext } from '../stringify/stringify.ts'
+import type { StringifyContext } from '../util.ts'
 import type { Alias } from './Alias.ts'
 import type { Scalar } from './Scalar.ts'
 import type { ToJSContext } from './toJS.ts'
-import type { MapLike, YAMLMap } from './YAMLMap.ts'
+import type { YAMLMap } from './YAMLMap.ts'
 import type { YAMLSeq } from './YAMLSeq.ts'
 
 export type Node = Alias | Scalar | YAMLSeq | YAMLMap
@@ -29,12 +29,12 @@ export type NodeType<T> = T extends
 
 export type Range = [start: number, valueEnd: number, nodeEnd: number]
 
-export abstract class NodeBase {
+export interface NodeBase {
   /** A comment on or immediately after this */
-  declare comment?: string | null
+  comment?: string | null
 
   /** A comment before this */
-  declare commentBefore?: string | null
+  commentBefore?: string | null
 
   /**
    * The `[start, value-end, node-end]` character offsets for the part of the
@@ -42,44 +42,26 @@ export abstract class NodeBase {
    * and `node-end` positions are themselves not included in their respective
    * ranges.
    */
-  declare range?: Range | null
+  range?: Range | null
 
   /** A blank line before this node and its commentBefore */
-  declare spaceBefore?: boolean
+  spaceBefore?: boolean
 
   /** The CST token that was composed into this node.  */
-  declare srcToken?: Token
+  srcToken?: Token
 
   /** A fully qualified tag, if required */
-  declare tag?: string
+  tag?: string
 
-  /**
-   * Customize the way that a key-value pair is resolved.
-   * Used for YAML 1.1 !!merge << handling.
-   */
-  declare addToJSMap?: (
-    doc: Document<DocValue, boolean>,
-    ctx: ToJSContext | undefined,
-    map: MapLike,
-    value: unknown
-  ) => void
+  /** Create a copy of this node.  */
+  clone(_schema?: Schema): this
 
   /** A plain JavaScript representation of this node. */
-  abstract toJS(doc: Document<DocValue, boolean>, opt?: ToJSContext): any
+  toJS(doc: Document<DocValue, boolean>, opt?: ToJSContext): any
 
-  abstract toString(
+  toString(
     ctx?: StringifyContext,
     onComment?: () => void,
     onChompKeep?: () => void
   ): string
-
-  /** Create a copy of this node.  */
-  clone(_schema?: Schema): NodeBase {
-    const copy: NodeBase = Object.create(
-      Object.getPrototypeOf(this),
-      Object.getOwnPropertyDescriptors(this)
-    )
-    if (this.range) copy.range = this.range.slice() as NodeBase['range']
-    return copy
-  }
 }
diff --git a/src/nodes/Pair.ts b/src/nodes/Pair.ts
index 07131aec..9296543a 100644
--- a/src/nodes/Pair.ts
+++ b/src/nodes/Pair.ts
@@ -5,12 +5,12 @@ import type { StringifyContext } from '../stringify/stringify.ts'
 import { stringifyPair } from '../stringify/stringifyPair.ts'
 import { addPairToJSMap } from './addPairToJSMap.ts'
 import type { NodeOf, Primitive } from './Collection.ts'
-import type { NodeBase } from './Node.ts'
+import type { Node } from './Node.ts'
 import type { ToJSContext } from './toJS.ts'
 
 export class Pair<
-  K extends Primitive | NodeBase = Primitive | NodeBase,
-  V extends Primitive | NodeBase = Primitive | NodeBase
+  K extends Primitive | Node = Primitive | Node,
+  V extends Primitive | Node = Primitive | Node
 > {
   key: NodeOf<K>
   value: NodeOf<V> | null
diff --git a/src/nodes/Scalar.ts b/src/nodes/Scalar.ts
index 20da8531..c82f91d5 100644
--- a/src/nodes/Scalar.ts
+++ b/src/nodes/Scalar.ts
@@ -1,6 +1,8 @@
+import type { Document, DocValue } from '../doc/Document.ts'
 import type { BlockScalar, FlowScalar } from '../parse/cst.ts'
-import { NodeBase } from './Node.ts'
+import type { NodeBase, Range } from './Node.ts'
 import type { ToJSContext } from './toJS.ts'
+import type { MapLike } from './YAMLMap.ts'
 
 export declare namespace Scalar {
   type BLOCK_FOLDED = 'BLOCK_FOLDED'
@@ -12,7 +14,7 @@ export declare namespace Scalar {
   type Type = BLOCK_FOLDED | BLOCK_LITERAL | PLAIN | QUOTE_DOUBLE | QUOTE_SINGLE
 }
 
-export class Scalar<T = unknown> extends NodeBase {
+export class Scalar<T = unknown> implements NodeBase {
   static readonly BLOCK_FOLDED = 'BLOCK_FOLDED'
   static readonly BLOCK_LITERAL = 'BLOCK_LITERAL'
   static readonly PLAIN = 'PLAIN'
@@ -24,6 +26,12 @@ export class Scalar<T = unknown> extends NodeBase {
   /** An optional anchor on this node. Used by alias nodes. */
   declare anchor?: string
 
+  /** A comment on or immediately after this node. */
+  declare comment?: string | null
+
+  /** A comment before this node. */
+  declare commentBefore?: string | null
+
   /**
    * By default (undefined), numbers use decimal notation.
    * The YAML 1.2 core schema only supports 'HEX' and 'OCT'.
@@ -34,19 +42,53 @@ export class Scalar<T = unknown> extends NodeBase {
   /** If `value` is a number, use this value when stringifying this node. */
   declare minFractionDigits?: number
 
+  /**
+   * The `[start, value-end, node-end]` character offsets for
+   * the part of the source parsed into this node (undefined if not parsed).
+   * The `value-end` and `node-end` positions are themselves not included in their respective ranges.
+   */
+  declare range?: Range | null
+
+  /** A blank line before this node and its commentBefore */
+  declare spaceBefore?: boolean
+
+  /** The CST token that was composed into this node.  */
+  declare srcToken?: FlowScalar | BlockScalar
+
   /** Set during parsing to the source string value */
   declare source?: string
 
-  declare srcToken?: FlowScalar | BlockScalar
+  /** A fully qualified tag, if required */
+  declare tag?: string
 
   /** The scalar style used for the node's string representation */
   declare type?: Scalar.Type
 
+  /**
+   * Customize the way that a key-value pair is resolved.
+   * Used for YAML 1.1 !!merge << handling.
+   */
+  declare addToJSMap?: (
+    doc: Document<DocValue, boolean>,
+    ctx: ToJSContext | undefined,
+    map: MapLike,
+    value: unknown
+  ) => void
+
   constructor(value: T) {
-    super()
     this.value = value
   }
 
+  /** Create a copy of this node.  */
+  clone(): this {
+    const copy: this = Object.create(
+      Object.getPrototypeOf(this),
+      Object.getOwnPropertyDescriptors(this)
+    )
+    if (this.range) copy.range = [...this.range]
+    return copy
+  }
+
   /** A plain JavaScript representation of this node. */
   toJS(_doc?: unknown, ctx?: ToJSContext): T {
     if (ctx && this.anchor) {
diff --git a/src/nodes/YAMLMap.ts b/src/nodes/YAMLMap.ts
index a14aac93..84bb77ea 100644
--- a/src/nodes/YAMLMap.ts
+++ b/src/nodes/YAMLMap.ts
@@ -6,7 +6,8 @@ import type { StringifyContext } from '../stringify/stringify.ts'
 import { stringifyCollection } from '../stringify/stringifyCollection.ts'
 import { addPairToJSMap } from './addPairToJSMap.ts'
 import { Collection, type NodeOf, type Primitive } from './Collection.ts'
-import { NodeBase } from './Node.ts'
+import { isNode } from './identity.ts'
+import type { Node, NodeBase } from './Node.ts'
 import { Pair } from './Pair.ts'
 import { Scalar } from './Scalar.ts'
 import { ToJSContext } from './toJS.ts'
@@ -17,8 +18,8 @@ export type MapLike =
   | Record<string | number | symbol, any>
 
 export function findPair<
-  K extends Primitive | NodeBase = Primitive | NodeBase,
-  V extends Primitive | NodeBase = Primitive | NodeBase
+  K extends Primitive | Node = Primitive | Node,
+  V extends Primitive | Node = Primitive | Node
 >(items: Iterable<Pair<K, V>>, key: unknown): Pair<K, V> | undefined {
   const k = key instanceof Scalar ? key.value : key
   for (const it of items) {
@@ -29,9 +30,12 @@ export function findPair<
 }
 
 export class YAMLMap<
-  K extends Primitive | NodeBase = Primitive | NodeBase,
-  V extends Primitive | NodeBase = Primitive | NodeBase
-> extends Collection {
+  K extends Primitive | Node = Primitive | Node,
+  V extends Primitive | Node = Primitive | Node
+>
+  extends Collection
+  implements NodeBase
+{
   static get tagName(): 'tag:yaml.org,2002:map' {
     return 'tag:yaml.org,2002:map'
   }
@@ -109,10 +113,7 @@ export class YAMLMap<
     options?: Omit<CreateNodeOptions, 'aliasDuplicateObjects'>
   ): void {
     let pair: Pair
-    if (
-      key instanceof NodeBase &&
-      (value instanceof NodeBase || value === null)
-    ) {
+    if (isNode(key) && (value === null || isNode(value))) {
       pair = new Pair(key, value)
     } else if (!this.schema) {
       throw new Error('Schema is required')
diff --git a/src/nodes/YAMLSeq.ts b/src/nodes/YAMLSeq.ts
index f122edfa..d083ac88 100644
--- a/src/nodes/YAMLSeq.ts
+++ b/src/nodes/YAMLSeq.ts
@@ -5,7 +5,8 @@ import type { BlockSequence, FlowCollection } from '../parse/cst.ts'
 import type { StringifyContext } from '../stringify/stringify.ts'
 import { stringifyCollection } from '../stringify/stringifyCollection.ts'
 import { Collection, type NodeOf, type Primitive } from './Collection.ts'
-import { NodeBase } from './Node.ts'
+import { isNode } from './identity.ts'
+import type { Node, NodeBase } from './Node.ts'
 import type { Pair } from './Pair.ts'
 import { Scalar } from './Scalar.ts'
 import { ToJSContext } from './toJS.ts'
@@ -14,8 +15,11 @@ const isScalarValue = (value: unknown): boolean =>
   !value || (typeof value !== 'function' && typeof value !== 'object')
 
 export class YAMLSeq<
-  T extends Primitive | NodeBase | Pair = Primitive | NodeBase | Pair
-> extends Collection {
+  T extends Primitive | Node | Pair = Primitive | Node | Pair
+>
+  extends Collection
+  implements NodeBase
+{
   static get tagName(): 'tag:yaml.org,2002:seq' {
     return 'tag:yaml.org,2002:seq'
   }
@@ -27,7 +31,7 @@ export class YAMLSeq<
     value: T,
     options?: Omit<CreateNodeOptions, 'aliasDuplicateObjects'>
   ): void {
-    if (value instanceof NodeBase) this.items.push(value as NodeOf<T>)
+    if (isNode(value)) this.items.push(value as NodeOf<T>)
     else if (!this.schema) throw new Error('Schema is required')
     else {
       const nc = new NodeCreator(this.schema, {
@@ -94,7 +98,7 @@ export class YAMLSeq<
     if (idx < 0) throw new RangeError(`Invalid negative index ${idx}`)
     const prev = this.items[idx]
     if (prev instanceof Scalar && isScalarValue(value)) prev.value = value
-    else if (value instanceof NodeBase) this.items[idx] = value as NodeOf<T>
+    else if (isNode(value)) this.items[idx] = value as NodeOf<T>
     else if (!this.schema) throw new Error('Schema is required')
     else {
       const nc = new NodeCreator(this.schema, {
diff --git a/src/nodes/addPairToJSMap.ts b/src/nodes/addPairToJSMap.ts
index 18dc0460..fd676b64 100644
--- a/src/nodes/addPairToJSMap.ts
+++ b/src/nodes/addPairToJSMap.ts
@@ -2,7 +2,7 @@ import type { Document, DocValue } from '../doc/Document.ts'
 import { warn } from '../log.ts'
 import { addMergeToJSMap, isMergeKey } from '../schema/yaml-1.1/merge.ts'
 import { createStringifyContext } from '../stringify/stringify.ts'
-import type { NodeBase } from './Node.ts'
+import type { Node } from './Node.ts'
 import type { Pair } from './Pair.ts'
 import type { ToJSContext } from './toJS.ts'
 import type { MapLike } from './YAMLMap.ts'
@@ -13,7 +13,7 @@ export function addPairToJSMap(
   map: MapLike,
   { key, value }: Pair
 ): MapLike {
-  if (key.addToJSMap) key.addToJSMap(doc, ctx, map, value)
+  if ('addToJSMap' in key) key.addToJSMap?.(doc, ctx, map, value)
   // TODO: Should drop this special case for bare << handling
   else if (isMergeKey(doc, key)) addMergeToJSMap(doc, ctx, map, value)
   else {
@@ -41,7 +41,7 @@ export function addPairToJSMap(
 function stringifyKey(
   doc: Document<DocValue, boolean>,
   ctx: ToJSContext,
-  key: NodeBase,
+  key: Node,
   jsKey: unknown
 ) {
   if (jsKey === null) return ''
diff --git a/src/nodes/identity.ts b/src/nodes/identity.ts
new file mode 100644
index 00000000..a3bb0314
--- /dev/null
+++ b/src/nodes/identity.ts
@@ -0,0 +1,8 @@
+import { Alias } from './Alias.ts'
+import { Collection } from './Collection.ts'
+import type { Node } from './Node.ts'
+import { Scalar } from './Scalar.ts'
+
+/** Type predicate for `Node` values */
+export const isNode = (node: unknown): node is Node =>
+  node instanceof Scalar || node instanceof Alias || node instanceof Collection
diff --git a/src/options.ts b/src/options.ts
index ef8a0aaf..1d20f556 100644
--- a/src/options.ts
+++ b/src/options.ts
@@ -1,7 +1,7 @@
 import type { Reviver } from './doc/applyReviver.ts'
 import type { Directives } from './doc/directives.ts'
 import type { LogLevelId } from './log.ts'
-import type { NodeBase } from './nodes/Node.ts'
+import type { Node } from './nodes/Node.ts'
 import type { Pair } from './nodes/Pair.ts'
 import type { Scalar } from './nodes/Scalar.ts'
 import type { LineCounter } from './parse/line-counter.ts'
@@ -67,7 +67,7 @@ export type ParseOptions = {
    *
    * Default: `true`
    */
-  uniqueKeys?: boolean | ((a: NodeBase, b: NodeBase) => boolean)
+  uniqueKeys?: boolean | ((a: Node, b: Node) => boolean)
 }
 
 export type DocumentOptions = {
diff --git a/src/schema/yaml-1.1/omap.ts b/src/schema/yaml-1.1/omap.ts
index d6656d6f..e65dc1aa 100644
--- a/src/schema/yaml-1.1/omap.ts
+++ b/src/schema/yaml-1.1/omap.ts
@@ -1,6 +1,6 @@
 import type { Document, DocValue } from '../../doc/Document.ts'
 import type { Primitive } from '../../nodes/Collection.ts'
-import type { NodeBase } from '../../nodes/Node.ts'
+import type { Node } from '../../nodes/Node.ts'
 import type { Pair } from '../../nodes/Pair.ts'
 import { Scalar } from '../../nodes/Scalar.ts'
 import type { ToJSContext } from '../../nodes/toJS.ts'
@@ -12,8 +12,8 @@ import type { CollectionTag } from '../types.ts'
 import { createPairs, resolvePairs } from './pairs.ts'
 
 export class YAMLOMap<
-  K extends Primitive | NodeBase = Primitive | NodeBase,
-  V extends Primitive | NodeBase = Primitive | NodeBase
+  K extends Primitive | Node = Primitive | Node,
+  V extends Primitive | Node = Primitive | Node
 > extends YAMLSeq<Pair<K, V>> {
   static tag = 'tag:yaml.org,2002:omap'
 
diff --git a/src/schema/yaml-1.1/pairs.ts b/src/schema/yaml-1.1/pairs.ts
index 6890e1be..293ca388 100644
--- a/src/schema/yaml-1.1/pairs.ts
+++ b/src/schema/yaml-1.1/pairs.ts
@@ -1,5 +1,5 @@
 import type { NodeCreator } from '../../doc/NodeCreator.ts'
-import type { NodeBase } from '../../nodes/Node.ts'
+import type { Node } from '../../nodes/Node.ts'
 import { Pair } from '../../nodes/Pair.ts'
 import { Scalar } from '../../nodes/Scalar.ts'
 import { YAMLMap } from '../../nodes/YAMLMap.ts'
@@ -30,7 +30,7 @@ export function resolvePairs(
         }
         seq.items[i] = pair
       } else {
-        seq.items[i] = new Pair<NodeBase, null>(item, null)
+        seq.items[i] = new Pair<Node, null>(item, null)
       }
     }
   } else onError('Expected a sequence for this tag')
diff --git a/src/schema/yaml-1.1/set.ts b/src/schema/yaml-1.1/set.ts
index 1a9bec73..2e47a55c 100644
--- a/src/schema/yaml-1.1/set.ts
+++ b/src/schema/yaml-1.1/set.ts
@@ -1,7 +1,8 @@
 import type { Document, DocValue } from '../../doc/Document.ts'
 import { NodeCreator } from '../../doc/NodeCreator.ts'
 import type { NodeOf, Primitive } from '../../nodes/Collection.ts'
-import { NodeBase } from '../../nodes/Node.ts'
+import { isNode } from '../../nodes/identity.ts'
+import type { Node } from '../../nodes/Node.ts'
 import { Pair } from '../../nodes/Pair.ts'
 import { Scalar } from '../../nodes/Scalar.ts'
 import type { ToJSContext } from '../../nodes/toJS.ts'
@@ -12,7 +13,7 @@ import type { StringifyContext } from '../../stringify/stringify.ts'
 import type { CollectionTag } from '../types.ts'
 
 export class YAMLSet<
-  T extends Primitive | NodeBase = Primitive | NodeBase
+  T extends Primitive | Node = Primitive | Node
 > extends YAMLMap<T, T> {
   static tag = 'tag:yaml.org,2002:set'
 
@@ -64,8 +65,8 @@ export class YAMLSet<
     if (prev && !value) {
       this.items.splice(this.items.indexOf(prev), 1)
     } else if (!prev && value) {
-      let node: NodeBase
-      if (key instanceof NodeBase) {
+      let node: Node
+      if (isNode(key)) {
         node = key
       } else if (!this.schema) {
         throw new Error('Schema is required')
@@ -100,7 +101,7 @@ export class YAMLSet<
       for (let value of iterable as Iterable<unknown>) {
         if (typeof nc.replacer === 'function')
           value = nc.replacer.call(iterable, value, value)
-        set.items.push(nc.createPair(value, null) as Pair<NodeBase, null>)
+        set.items.push(nc.createPair(value, null) as Pair<Node, null>)
       }
     return set
   }
diff --git a/src/stringify/stringify.ts b/src/stringify/stringify.ts
index c44e0c47..6983ae19 100644
--- a/src/stringify/stringify.ts
+++ b/src/stringify/stringify.ts
@@ -2,7 +2,7 @@ import { anchorIsValid } from '../doc/anchors.ts'
 import type { Document } from '../doc/Document.ts'
 import { Alias } from '../nodes/Alias.ts'
 import { Collection } from '../nodes/Collection.ts'
-import { NodeBase, type Node } from '../nodes/Node.ts'
+import type { Node } from '../nodes/Node.ts'
 import { Pair } from '../nodes/Pair.ts'
 import { Scalar } from '../nodes/Scalar.ts'
 import type { ToStringOptions } from '../options.ts'
@@ -131,31 +131,26 @@ function stringifyProps(
 }
 
 export function stringify(
-  item: unknown,
+  node: Node | Pair | null,
   ctx: StringifyContext,
   onComment?: () => void,
   onChompKeep?: () => void
 ): string {
-  if (item instanceof Pair) return item.toString(ctx, onComment, onChompKeep)
-  if (item instanceof Alias) {
-    if (ctx.doc.directives) return item.toString(ctx)
-
-    if (ctx.resolvedAliases?.has(item)) {
-      throw new TypeError(
-        `Cannot stringify circular structure without alias nodes`
-      )
-    } else {
-      if (ctx.resolvedAliases) ctx.resolvedAliases.add(item)
-      else ctx.resolvedAliases = new Set([item])
-      item = item.resolve(ctx.doc)
+  if (node instanceof Pair) return node.toString(ctx, onComment, onChompKeep)
+  if (node instanceof Alias) {
+    if (ctx.doc.directives) return node.toString(ctx)
+    if (ctx.resolvedAliases?.has(node)) {
+      const msg = 'Cannot stringify circular structure without alias nodes'
+      throw new TypeError(msg)
     }
+
+    if (ctx.resolvedAliases) ctx.resolvedAliases.add(node)
+    else ctx.resolvedAliases = new Set([node])
+    node = node.resolve(ctx.doc) ?? null
   }
 
   let tagObj: ScalarTag | CollectionTag | undefined = undefined
-  const node =
-    item instanceof NodeBase
-      ? (item as Node)
-      : ctx.doc.createNode(item, { onTagObj: o => (tagObj = o) })
+  node ??= ctx.doc.createNode(null, { onTagObj: o => (tagObj = o) })
   tagObj ??= getTagObject(ctx.doc.schema.tags, node)
 
   const props = stringifyProps(node, tagObj, ctx)
diff --git a/src/stringify/stringifyCollection.ts b/src/stringify/stringifyCollection.ts
index 895b4c34..133d5572 100644
--- a/src/stringify/stringifyCollection.ts
+++ b/src/stringify/stringifyCollection.ts
@@ -1,5 +1,4 @@
 import type { Collection } from '../nodes/Collection.ts'
-import { NodeBase } from '../nodes/Node.ts'
 import { Pair } from '../nodes/Pair.ts'
 import type { StringifyContext } from './stringify.ts'
 import { stringify } from './stringify.ts'
@@ -45,16 +44,13 @@ function stringifyBlockCollection(
   for (let i = 0; i < items.length; ++i) {
     const item = items[i]
     let comment: string | null = null
-    if (item instanceof NodeBase) {
+    if (item instanceof Pair) {
+      if (!chompKeep && item.key.spaceBefore) lines.push('')
+      addCommentBefore(ctx, lines, item.key.commentBefore, chompKeep)
+    } else if (item) {
       if (!chompKeep && item.spaceBefore) lines.push('')
       addCommentBefore(ctx, lines, item.commentBefore, chompKeep)
       if (item.comment) comment = item.comment
-    } else if (item instanceof Pair) {
-      const ik = item.key instanceof NodeBase ? item.key : null
-      if (ik) {
-        if (!chompKeep && ik.spaceBefore) lines.push('')
-        addCommentBefore(ctx, lines, ik.commentBefore, chompKeep)
-      }
     }
 
     chompKeep = false
@@ -112,25 +108,23 @@ function stringifyFlowCollection(
   for (let i = 0; i < items.length; ++i) {
     const item = items[i]
     let comment: string | null = null
-    if (item instanceof NodeBase) {
-      if (item.spaceBefore) lines.push('')
-      addCommentBefore(ctx, lines, item.commentBefore, false)
-      if (item.comment) comment = item.comment
-    } else if (item instanceof Pair) {
-      const ik = item.key instanceof NodeBase ? item.key : null
-      if (ik) {
-        if (ik.spaceBefore) lines.push('')
-        addCommentBefore(ctx, lines, ik.commentBefore, false)
-        if (ik.comment) reqNewline = true
-      }
+    if (item instanceof Pair) {
+      const ik = item.key
+      if (ik.spaceBefore) lines.push('')
+      addCommentBefore(ctx, lines, ik.commentBefore, false)
+      if (ik.comment) reqNewline = true
 
-      const iv = item.value instanceof NodeBase ? item.value : null
+      const iv = item.value
       if (iv) {
         if (iv.comment) comment = iv.comment
         if (iv.commentBefore) reqNewline = true
-      } else if (item.value == null && ik?.comment) {
+      } else if (ik?.comment) {
         comment = ik.comment
       }
+    } else if (item) {
+      if (item.spaceBefore) lines.push('')
+      addCommentBefore(ctx, lines, item.commentBefore, false)
+      if (item.comment) comment = item.comment
     }
 
     if (comment) reqNewline = true
diff --git a/src/stringify/stringifyPair.ts b/src/stringify/stringifyPair.ts
index b47ce38b..109cabbf 100644
--- a/src/stringify/stringifyPair.ts
+++ b/src/stringify/stringifyPair.ts
@@ -1,5 +1,4 @@
 import { Collection } from '../nodes/Collection.ts'
-import { NodeBase } from '../nodes/Node.ts'
 import type { Pair } from '../nodes/Pair.ts'
 import { Scalar } from '../nodes/Scalar.ts'
 import { YAMLSeq } from '../nodes/YAMLSeq.ts'
@@ -14,29 +13,23 @@ export function stringifyPair(
   onChompKeep?: () => void
 ): string {
   const {
-    doc,
     indent,
     indentStep,
     noValues,
     options: { commentString, indentSeq, simpleKeys }
   } = ctx
-  let keyComment = (key instanceof NodeBase && key.comment) || null
   if (simpleKeys) {
-    if (keyComment) {
+    if (key.comment) {
       throw new Error('With simple keys, key nodes cannot have comments')
     }
-    if (
-      key instanceof Collection ||
-      (!(key instanceof NodeBase) && typeof key === 'object')
-    ) {
+    if (key instanceof Collection) {
       const msg = 'With simple keys, collection cannot be used as a key value'
       throw new Error(msg)
     }
   }
   let explicitKey =
     !simpleKeys &&
-    (!key ||
-      !(key instanceof Scalar) ||
+    (!(key instanceof Scalar) ||
       key.type === Scalar.BLOCK_FOLDED ||
       key.type === Scalar.BLOCK_LITERAL)
 
@@ -46,6 +39,7 @@ export function stringifyPair(
     indent: indent + indentStep,
     noValues: false
   }
+  let keyComment = key.comment
   let keyCommentDone = false
   let chompKeep = false
   let str = stringify(
@@ -94,7 +88,7 @@ export function stringifyPair(
   }
 
   let vsb, vcb, valueComment
-  if (value instanceof NodeBase) {
+  if (value) {
     vsb = !!value.spaceBefore
     vcb = value.commentBefore
     valueComment = value.comment
@@ -102,7 +96,6 @@ export function stringifyPair(
     vsb = false
     vcb = null
     valueComment = null
-    if (value && typeof value === 'object') value = doc.createNode(value)
   }
   ctx.implicitKey = false
   if (!explicitKey && !keyComment && value instanceof Scalar)
diff --git a/src/test-events.ts b/src/test-events.ts
index 60770462..41645f27 100644
--- a/src/test-events.ts
+++ b/src/test-events.ts
@@ -1,7 +1,8 @@
 import type { Document } from './doc/Document.ts'
 import { Alias } from './nodes/Alias.ts'
 import { Collection } from './nodes/Collection.ts'
-import { type Node, NodeBase } from './nodes/Node.ts'
+import { isNode } from './nodes/identity.ts'
+import type { Node } from './nodes/Node.ts'
 import { Pair } from './nodes/Pair.ts'
 import { Scalar } from './nodes/Scalar.ts'
 import { YAMLMap } from './nodes/YAMLMap.ts'
@@ -68,13 +69,13 @@ function addEvents(
   events: string[],
   doc: Document,
   errPos: number,
-  node: NodeBase | Pair | null
+  node: Node | Pair | null
 ) {
   if (!node) {
     events.push('=VAL :')
     return
   }
-  if (errPos !== -1 && node instanceof NodeBase && node.range![0] >= errPos)
+  if (errPos !== -1 && isNode(node) && node.range![0] >= errPos)
     throw new Error()
   let props = ''
   let anchor =
@@ -88,7 +89,7 @@ function addEvents(
     }
     props = ` &${anchor}`
   }
-  if (node instanceof NodeBase && node.tag) props += ` <${node.tag}>`
+  if (isNode(node) && node.tag) props += ` <${node.tag}>`
 
   if (node instanceof YAMLMap) {
     const ev = node.flow ? '+MAP {}' : '+MAP'
diff --git a/src/visit.ts b/src/visit.ts
index 2721022f..c5014747 100644
--- a/src/visit.ts
+++ b/src/visit.ts
@@ -1,6 +1,7 @@
 import { Document, type DocValue } from './doc/Document.ts'
 import { Alias } from './nodes/Alias.ts'
-import { NodeBase, type Node } from './nodes/Node.ts'
+import { isNode } from './nodes/identity.ts'
+import type { Node } from './nodes/Node.ts'
 import { Pair } from './nodes/Pair.ts'
 import { Scalar } from './nodes/Scalar.ts'
 import { YAMLMap } from './nodes/YAMLMap.ts'
@@ -17,7 +18,7 @@ export type visitorFn<T> = (
 ) => void | symbol | number | Node | Pair
 
 export type visitor =
-  | visitorFn<unknown>
+  | visitorFn<Node | Pair | null>
   | {
       Alias?: visitorFn<Alias>
       Collection?: visitorFn<YAMLMap | YAMLSeq>
@@ -42,7 +43,7 @@ export type asyncVisitorFn<T> = (
   | Promise<void | symbol | number | Node | Pair>
 
 export type asyncVisitor =
-  | asyncVisitorFn<unknown>
+  | asyncVisitorFn<Node | Pair | null>
   | {
       Alias?: asyncVisitorFn<Alias>
       Collection?: asyncVisitorFn<YAMLMap | YAMLSeq>
@@ -109,13 +110,13 @@ visit.REMOVE = REMOVE
 
 function visit_(
   key: number | 'key' | 'value' | null,
-  node: unknown,
+  node: Node | Pair | null,
   visitor: visitor,
   path: readonly (Document | Node | Pair)[]
 ): number | symbol | void {
   const ctrl = callVisitor(key, node, visitor, path)
 
-  if (ctrl instanceof NodeBase || ctrl instanceof Pair) {
+  if (isNode(ctrl) || ctrl instanceof Pair) {
     replaceNode(key, path, ctrl)
     return visit_(key, ctrl, visitor, path)
   }
@@ -208,13 +209,13 @@ visitAsync.REMOVE = REMOVE
 
 async function visitAsync_(
   key: number | 'key' | 'value' | null,
-  node: unknown,
+  node: Node | Pair | null,
   visitor: asyncVisitor,
   path: readonly (Document | Node | Pair)[]
 ): Promise<number | symbol | void> {
   const ctrl = await callVisitor(key, node, visitor, path)
 
-  if (ctrl instanceof NodeBase || ctrl instanceof Pair) {
+  if (isNode(ctrl) || ctrl instanceof Pair) {
     replaceNode(key, path, ctrl)
     return visitAsync_(key, ctrl, visitor, path)
   }
@@ -275,19 +276,19 @@ function initVisitor<V extends visitor | asyncVisitor>(visitor: V) {
 
 function callVisitor(
   key: number | 'key' | 'value' | null,
-  node: unknown,
+  node: Node | Pair | null,
   visitor: visitor,
   path: readonly (Document | Node | Pair)[]
 ): ReturnType<visitorFn<unknown>>
 function callVisitor(
   key: number | 'key' | 'value' | null,
-  node: unknown,
+  node: Node | Pair | null,
   visitor: asyncVisitor,
   path: readonly (Document | Node | Pair)[]
 ): ReturnType<asyncVisitorFn<unknown>>
 function callVisitor(
   key: number | 'key' | 'value' | null,
-  node: unknown,
+  node: Node | Pair | null,
   visitor: visitor | asyncVisitor,
   path: readonly (Document | Node | Pair)[]
 ): ReturnType<visitorFn<unknown>> | ReturnType<asyncVisitorFn<unknown>> {
@@ -309,7 +310,7 @@ function replaceNode(
   if (parent instanceof YAMLMap || parent instanceof YAMLSeq) {
     parent.items[key as number] = node
   } else if (parent instanceof Pair) {
-    if (node instanceof NodeBase) {
+    if (isNode(node)) {
       if (key === 'key') parent.key = node
       else parent.value = node
     } else {
diff --git a/tests/doc/anchors.ts b/tests/doc/anchors.ts
index 956dbd8d..b1386700 100644
--- a/tests/doc/anchors.ts
+++ b/tests/doc/anchors.ts
@@ -117,6 +117,7 @@ describe('errors', () => {
     const node = doc.value.items[0]
     const alias = doc.createAlias(node, 'AA')
     expect(() => {
+      // @ts-expect-error This is intentionally wrong.
       alias.tag = 'tag:yaml.org,2002:alias'
     }).toThrow('Alias nodes cannot have tags')
   })
diff --git a/tests/doc/createNode.ts b/tests/doc/createNode.ts
index 9635e11e..842c64ce 100644
--- a/tests/doc/createNode.ts
+++ b/tests/doc/createNode.ts
@@ -85,8 +85,6 @@ describe('arrays', () => {
       const res = '- 3\n- - four\n  - 5\n'
       const doc = new Document(array)
       expect(String(doc)).toBe(res)
-      doc.value = array as any
-      expect(String(doc)).toBe(res)
       doc.value = doc.createNode(array)
       expect(String(doc)).toBe(res)
     })
@@ -180,8 +178,6 @@ z:
   v: 6\n`
       const doc = new Document(object)
       expect(String(doc)).toBe(res)
-      doc.value = object as any
-      expect(String(doc)).toBe(res)
       doc.value = doc.createNode(object)
       expect(String(doc)).toBe(res)
     })
@@ -215,8 +211,6 @@ describe('Set', () => {
       const res = '- 3\n- - four\n  - 5\n'
       const doc = new Document(set)
       expect(String(doc)).toBe(res)
-      doc.value = set as any
-      expect(String(doc)).toBe(res)
       doc.value = doc.createNode(set)
       expect(String(doc)).toBe(res)
     })
@@ -293,8 +287,6 @@ y:
 : z\n`
       const doc = new Document(map)
       expect(String(doc)).toBe(res)
-      doc.value = map as any
-      expect(String(doc)).toBe(res)
       doc.value = doc.createNode(map)
       expect(String(doc)).toBe(res)
     })
diff --git a/tests/doc/stringify.ts b/tests/doc/stringify.ts
index f91e565d..1c791440 100644
--- a/tests/doc/stringify.ts
+++ b/tests/doc/stringify.ts
@@ -752,25 +752,7 @@ describe('simple keys', () => {
     )
   })
 
-  test('key with JS object value', () => {
-    const doc = YAML.parseDocument<any>('[foo]: bar')
-    doc.value.items[0].key = { foo: 42 }
-    expect(doc.toString()).toBe('? foo: 42\n: bar\n')
-    expect(() => doc.toString({ simpleKeys: true })).toThrow(
-      /With simple keys, collection cannot be used as a key value/
-    )
-  })
-
-  test('key with JS null value', () => {
-    const doc = YAML.parseDocument<any>('[foo]: bar')
-    doc.value.items[0].key = null
-    expect(doc.toString()).toBe('? null\n: bar\n')
-    expect(() => doc.toString({ simpleKeys: true })).toThrow(
-      /With simple keys, collection cannot be used as a key value/
-    )
-  })
-
-  test('key value lingth > 1024', () => {
+  test('key value length > 1024', () => {
     const str = `
     ? ${new Array(1026).join('a')}
     : longkey`
diff --git a/tests/doc/types.ts b/tests/doc/types.ts
index c16aeab1..31a3cf28 100644
--- a/tests/doc/types.ts
+++ b/tests/doc/types.ts
@@ -980,8 +980,7 @@ describe('custom tags', () => {
       doc.value.items[3].comment = 'cc'
       const s = new Scalar(6)
       s.tag = '!g'
-      // @ts-expect-error TS should complain here
-      doc.value.items.splice(1, 1, s, '7')
+      doc.value.items.splice(1, 1, s, new Scalar('7'))
       expect(String(doc)).toBe(source`
         %TAG !e! tag:example.com,2000:test/
         %TAG !f! tag:example.com,2000:other/