@@ -44,5 +44,5 @@ PyTypeObject PyBaseObject_Type = PY_TRUFFLE_TYPE("object", &PyType_Type, Py_TPFL
 PyTypeObject PySuper_Type = PY_TRUFFLE_TYPE("super", &PyType_Type, Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE);
 
 int PyType_IsSubtype(PyTypeObject* a, PyTypeObject* b) {
-    return as_int(truffle_invoke(PY_TRUFFLE_CEXT, "PyType_IsSubtype", to_java((PyObject*)a), to_java((PyObject*)b)));
+    return polyglot_as_i32(polyglot_invoke(PY_TRUFFLE_CEXT, "PyType_IsSubtype", to_java((PyObject*)a), to_java((PyObject*)b)));
 }
@@ -680,7 +680,7 @@ def PyObject_Repr(o):
 
 
 def PyType_IsSubtype(a, b):
-    return b in a.mro()
+    return 1 if b in a.mro() else 0
 
 
 @may_raise
Original file line number	Diff line number	Diff line change
`@@ -44,5 +44,5 @@ PyTypeObject PyBaseObject_Type = PY_TRUFFLE_TYPE("object", &PyType_Type, Py_TPFL`
`44`	`44`	`PyTypeObject PySuper_Type = PY_TRUFFLE_TYPE("super", &PyType_Type, Py_TPFLAGS_DEFAULT \| Py_TPFLAGS_HAVE_GC \| Py_TPFLAGS_BASETYPE);`
`45`	`45`
`46`	`46`	`int PyType_IsSubtype(PyTypeObject* a, PyTypeObject* b) {`
`47`		`- return as_int(truffle_invoke(PY_TRUFFLE_CEXT, "PyType_IsSubtype", to_java((PyObject)a), to_java((PyObject)b)));`
	`47`	`+ return polyglot_as_i32(polyglot_invoke(PY_TRUFFLE_CEXT, "PyType_IsSubtype", to_java((PyObject)a), to_java((PyObject)b)));`
`48`	`48`	`}`