diff --git a/Python/codecs.c b/Python/codecs.c
index ceff376..20df522 100644
--- a/Python/codecs.c
+++ b/Python/codecs.c
@@ -82,7 +82,7 @@
 static
 PyObject *normalizestring(const char *string)
 {
-    register int i;
+    register size_t i;
     size_t len = strlen(string);
     char *p;
     PyObject *v;