diff --git a/lib/src/ffi.dart b/lib/src/ffi.dart
index f667520..f7c8d36 100644
--- a/lib/src/ffi.dart
+++ b/lib/src/ffi.dart
@@ -27,9 +27,14 @@ abstract class JSRef {
     _refCount++;
   }
 
+  bool _released = false;
+
   void free() {
     _refCount--;
-    if (_refCount < 0) destroy();
+    if (_refCount < 0 && !_released){
+      _released = true;
+      destroy();
+    }
   }
 
   void destroy();
diff --git a/lib/src/object.dart b/lib/src/object.dart
index c81d311..e939489 100644
--- a/lib/src/object.dart
+++ b/lib/src/object.dart
@@ -150,8 +150,12 @@ class _JSObject extends JSRef {
 }
 
 /// JS function wrapper
-class _JSFunction extends _JSObject implements JSInvokable, _IsolateEncodable {
-  _JSFunction(Pointer<JSContext> ctx, Pointer<JSValue> val) : super(ctx, val);
+class _JSFunction extends _JSObject implements JSInvokable, _IsolateEncodable, Finalizable {
+  _JSFunction(Pointer<JSContext> ctx, Pointer<JSValue> val) : super(ctx, val) {
+    _finalizer.attach(this, this);
+  }
+
+  static final _finalizer = Finalizer<_JSFunction>((f) => f.free());
 
   @override
   invoke(List<dynamic> arguments, [dynamic thisVal]) {