diff --git a/src/cffi.cpp b/src/cffi.cpp
index 49795d32..8135df43 100644
--- a/src/cffi.cpp
+++ b/src/cffi.cpp
@@ -125,18 +125,19 @@ namespace pkpy{
 
     void C99Struct::_register(VM* vm, PyObject* mod, PyObject* type){
         vm->bind_constructor<-1>(type, [](VM* vm, ArgsView args){
+            Type cls = PK_OBJ_GET(Type, args[0]);
             if(args.size() == 1+1){
                 if(is_int(args[1])){
                     int size = _CAST(int, args[1]);
-                    return VAR_T(C99Struct, size);
+                    return vm->heap.gcnew<C99Struct>(cls, size);
                 }
                 if(is_non_tagged_type(args[1], vm->tp_str)){
                     const Str& s = _CAST(Str&, args[1]);
-                    return VAR_T(C99Struct, (void*)s.data, s.size);
+                    return vm->heap.gcnew<C99Struct>(cls, (void*)s.data, s.size);
                 }
                 if(is_non_tagged_type(args[1], vm->tp_bytes)){
                     const Bytes& b = _CAST(Bytes&, args[1]);
-                    return VAR_T(C99Struct, (void*)b.data(), b.size());
+                    return vm->heap.gcnew<C99Struct>(cls, (void*)b.data(), b.size());
                 }
                 vm->TypeError("expected int, str or bytes");
                 return vm->None;
@@ -144,7 +145,7 @@ namespace pkpy{
             if(args.size() == 1+2){
                 void* p = CAST(void*, args[1]);
                 int size = CAST(int, args[2]);
-                return VAR_T(C99Struct, p, size);
+                return vm->heap.gcnew<C99Struct>(cls, p, size);
             }
             vm->TypeError("expected 1 or 2 arguments");
             return vm->None;
diff --git a/tests/80_c.py b/tests/80_c.py
index 35e6d464..6abfdf4e 100644
--- a/tests/80_c.py
+++ b/tests/80_c.py
@@ -32,4 +32,27 @@ for i in range(10):
     assert array2.offset(i).read_char() == 0
 
 c.free(array)
-c.free(array2)
\ No newline at end of file
+c.free(array2)
+
+class Vec2(c.struct):
+    def __new__(cls, x: float, y: float):
+        obj = c.struct.__new__(cls, 8)
+        obj.write_float(x, 0)
+        obj.write_float(y, 4)
+        return obj
+
+    @property
+    def x(self) -> float:
+        return self.read_float(0)
+    
+    @property
+    def y(self) -> float:
+        return self.read_float(4)
+    
+    def __repr__(self) -> str:
+        return f"Vec2({self.x}, {self.y})"
+    
+a = Vec2(1, 2)
+assert isinstance(a, c.struct)
+assert type(a) is Vec2
+assert repr(a) == "Vec2(1.0, 2.0)"