diff --git a/Python/modsupport.c b/Python/modsupport.c
index e291014..1aa3df2 100644
--- a/Python/modsupport.c
+++ b/Python/modsupport.c
@@ -421,7 +421,7 @@
 							"string too long for Python string");
 						return NULL;
 					}
-					n = (int)m;
+					n = (Py_ssize_t)m;
 				}
 				v = PyString_FromStringAndSize(str, n);
 			}