diff --git a/pkg/dart2wasm/lib/transformers.dart b/pkg/dart2wasm/lib/transformers.dart
index 2bf6a1d9cf3..b31fa85e5c6 100644
--- a/pkg/dart2wasm/lib/transformers.dart
+++ b/pkg/dart2wasm/lib/transformers.dart
@@ -590,7 +590,7 @@ class _WasmTransformer extends Transformer {
           ReturnStatement(VariableGet(whereKeep)),
         ]),
         positionalParameters: [whereFilterArg],
-        returnType: coreTypes.objectNullableRawType));
+        returnType: coreTypes.boolNonNullableRawType));
 
     Procedure whereProc =
         coreTypes.index.getProcedure('dart:async', 'Stream', 'where');
diff --git a/pkg/front_end/testcases/dart2wasm/yield.dart.strong.transformed.expect b/pkg/front_end/testcases/dart2wasm/yield.dart.strong.transformed.expect
index c1126bdc3a3..7740bb838b7 100644
--- a/pkg/front_end/testcases/dart2wasm/yield.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/dart2wasm/yield.dart.strong.transformed.expect
@@ -104,7 +104,7 @@ static method asyncMethod(asy::Stream<core::int> stream) → asy::Stream<core::i
     if(!#isEven)
       value.{asy::Completer::complete}(#C2){([FutureOr<core::bool>?]) → void};
     return value;
-  }){((core::Object?) → FutureOr<core::Object?>) → asy::Stream<core::Object?>}.{asy::Stream::where}((synthesized core::Object? value) → core::Object? {
+  }){((core::Object?) → FutureOr<core::Object?>) → asy::Stream<core::Object?>}.{asy::Stream::where}((synthesized core::Object? value) → core::bool {
     if(#isFirst) {
       #isFirst = #C1;
       return #C1;