strlen() returns a size_t, get rid of 64-bit warning
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index 259a423..b34dd52 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -136,7 +136,7 @@
 static int
 check_the_mode(char *mode)
 {
-	unsigned int len = strlen(mode);
+	size_t len = strlen(mode);
 
 	switch (len) {
 	case 0: