diff --git a/tests/run/ctruthtests.pyx b/tests/run/ctruthtests.pyx
index 499519824626a8679666ec18f760a9a9c032ffd9..fdb6e92e598c79896a161824e97fbe83d43c7ff5 100644
--- a/tests/run/ctruthtests.pyx
+++ b/tests/run/ctruthtests.pyx
@@ -78,7 +78,7 @@ def test_attr_int(TestExtInt e):
         return False
 
 ctypedef union _aux:
-    int i
+    size_t i
     void *p
 
 cdef class TestExtPtr: