diff --git a/isisd/isis_events.h b/isisd/isis_events.h
index a6ec2e8..c4bd8ab 100644
--- a/isisd/isis_events.h
+++ b/isisd/isis_events.h
@@ -50,6 +50,6 @@
 #define AUTH_ERROR_TYPE_SNP   2
 #define AUTH_ERROR_TYPE_HELLO 1
 void isis_event_auth_failure (char *area_tag, char *error_string,
-			      char *sysid);
+			      u_char *sysid);
 
 #endif /* _ZEBRA_ISIS_EVENTS_H */