fix warnings
diff --git a/skeletons/OCTET_STRING.h b/skeletons/OCTET_STRING.h
index 59f8848..63e7da8 100644
--- a/skeletons/OCTET_STRING.h
+++ b/skeletons/OCTET_STRING.h
@@ -13,7 +13,7 @@
 
 typedef struct OCTET_STRING {
 	uint8_t *buf;	/* Buffer with consecutive OCTET_STRING bits */
-	int size;	/* Size of the buffer */
+	size_t size;	/* Size of the buffer */
 
 	asn_struct_ctx_t _asn_ctx;	/* Parsing across buffer boundaries */
 } OCTET_STRING_t;