diff --git a/nnotepad/res/webnn.idl b/nnotepad/res/webnn.idl
index de986729..376dd8d3 100644
--- a/nnotepad/res/webnn.idl
+++ b/nnotepad/res/webnn.idl
@@ -439,6 +439,7 @@ dictionary MLPool2dOptions {
   sequence<[EnforceRange] unsigned long> dilations;
   MLInputOperandLayout layout = "nchw";
   MLRoundingType roundingType = "floor";
+  MLRoundingType outputShapeRounding = "floor";
   sequence<[EnforceRange] unsigned long> outputSizes;
 };