diff --git a/bindings/python/clang/cindex.py b/bindings/python/clang/cindex.py
index f3e230e..fc32394 100644
--- a/bindings/python/clang/cindex.py
+++ b/bindings/python/clang/cindex.py
@@ -3128,7 +3128,7 @@
 
   ("clang_Type_getSizeOf",
    [Type],
-   c_ulonglong),
+   c_longlong),
 ]
 
 class LibclangError(Exception):