diff --git a/napi-inl.h b/napi-inl.h
index be20dc085..e7ddce7f6 100644
--- a/napi-inl.h
+++ b/napi-inl.h
@@ -1315,7 +1315,7 @@ inline bool Object::Delete(uint32_t index) {
   return result;
 }
 
-inline Array Object::GetPropertyNames() const {
+inline Array Object::GetPropertyNames() {
   napi_value result;
   napi_status status = napi_get_property_names(_env, _value, &result);
   NAPI_THROW_IF_FAILED(_env, status, Array());
@@ -1345,7 +1345,7 @@ inline bool Object::DefineProperties(
   return true;
 }
 
-inline bool Object::InstanceOf(const Function& constructor) const {
+inline bool Object::InstanceOf(const Function& constructor) {
   bool result;
   napi_status status = napi_instanceof(_env, _value, constructor, &result);
   NAPI_THROW_IF_FAILED(_env, status, false);
diff --git a/napi.h b/napi.h
index 8be2ca3f7..702c3ce52 100644
--- a/napi.h
+++ b/napi.h
@@ -738,7 +738,7 @@ namespace Napi {
       uint32_t index ///< Property / element index
     );
 
-    Array GetPropertyNames() const; ///< Get all property names
+    Array GetPropertyNames();  ///< Get all property names
 
     /// Defines a property on the object.
     bool DefineProperty(
@@ -761,9 +761,8 @@ namespace Napi {
     /// Checks if an object is an instance created by a constructor function.
     ///
     /// This is equivalent to the JavaScript `instanceof` operator.
-    bool InstanceOf(
-      const Function& constructor ///< Constructor function
-    ) const;
+    bool InstanceOf(const Function& constructor  ///< Constructor function
+    );
 
     template <typename Finalizer, typename T>
     inline void AddFinalizer(Finalizer finalizeCallback, T* data);