diff --git a/src/utils/wpa_debug.c b/src/utils/wpa_debug.c
index 3b71d10b1..5511ef193 100644
--- a/src/utils/wpa_debug.c
+++ b/src/utils/wpa_debug.c
@@ -338,7 +338,7 @@ static void _wpa_hexdump(int level, const char *title, const u8 *buf,
 		}
 
 		syslog(syslog_priority(level), "%s - hexdump(len=%lu):%s",
-		       title, len, display);
+		       title, (unsigned long) len, display);
 		os_free(strbuf);
 		return;
 	}