diff --git a/asn1c/asn1c.c b/asn1c/asn1c.c
index 36916a1..a55cde4 100644
--- a/asn1c/asn1c.c
+++ b/asn1c/asn1c.c
@@ -253,7 +253,7 @@
 			 * ./asn1c/asn1c -> ./skeletons
 			 */
 			char *p;
-			int len;
+			size_t len;
 
 			p = a1c_dirname(av[-optind]);