diff --git a/runtime/src/main/cpp/Types.h b/runtime/src/main/cpp/Types.h
index a6ccd8c3468..d05e7ae3404 100644
--- a/runtime/src/main/cpp/Types.h
+++ b/runtime/src/main/cpp/Types.h
@@ -108,6 +108,7 @@ extern const TypeInfo* theUnitTypeInfo;
 extern const TypeInfo* theWorkerBoundReferenceTypeInfo;
 
 KBoolean IsInstance(const ObjHeader* obj, const TypeInfo* type_info) RUNTIME_PURE;
+KBoolean IsInstanceOfClassFast(const ObjHeader* obj, int32_t lo, int32_t hi) RUNTIME_PURE;
 void CheckCast(const ObjHeader* obj, const TypeInfo* type_info);
 KBoolean IsArray(KConstRef obj) RUNTIME_PURE;
 bool IsSubInterface(const TypeInfo* thiz, const TypeInfo* other) RUNTIME_PURE;