diff --git a/pydust/src/pytypes.zig b/pydust/src/pytypes.zig
index 77e3ad50..4d9e2707 100644
--- a/pydust/src/pytypes.zig
+++ b/pydust/src/pytypes.zig
@@ -267,12 +267,11 @@ fn Slots(comptime definition: type, comptime name: [:0]const u8) type {
             return 0;
         }
 
-        fn tp_init_default(pyself: *ffi.PyObject, pyargs: [*c]ffi.PyObject, pykwargs: [*c]ffi.PyObject) callconv(.C) ?*ffi.PyObject {
+        fn tp_init_default(pyself: *ffi.PyObject, pyargs: [*c]ffi.PyObject, pykwargs: [*c]ffi.PyObject) callconv(.C) c_int {
             _ = pyself;
             _ = pykwargs;
             _ = pyargs;
-            py.TypeError.raise("Native type cannot be instantiated from Python") catch return null;
-            return null;
+            py.TypeError.raise("Native type cannot be instantiated from Python") catch return -1;
         }
 
         /// Wrapper for the user's __del__ function.
diff --git a/test/test_classes.py b/test/test_classes.py
index 1d0bd606..1a7c5319 100644
--- a/test/test_classes.py
+++ b/test/test_classes.py
@@ -29,6 +29,11 @@ def test_constructor():
 # --8<-- [end:constructor]
 
 
+def test_non_constructable():
+    with pytest.raises(TypeError):
+        classes.SomeClass()
+
+
 # --8<-- [start:subclass]
 def test_subclasses():
     d = classes.Dog("labrador")