diff --git a/path.c b/path.c
index f613d8bbd1..56be5e1726 100644
--- a/path.c
+++ b/path.c
@@ -58,7 +58,7 @@ static void strbuf_cleanup_path(struct strbuf *sb)
 
 static int dir_prefix(const char *buf, const char *dir)
 {
-	int len = strlen(dir);
+	size_t len = strlen(dir);
 	return !strncmp(buf, dir, len) &&
 		(is_dir_sep(buf[len]) || buf[len] == '\0');
 }