diff --git a/servers/pm/main.c b/servers/pm/main.c
index 45796594c..ac140b92a 100644
--- a/servers/pm/main.c
+++ b/servers/pm/main.c
@@ -96,7 +96,8 @@ int main()
 				result = SUSPEND;	/* don't reply */
 				break;
 			default :
-				result = ENOSYS;
+				/* ignore notify() from unknown sender */
+				result = SUSPEND;
 		}
 
 		/* done, send reply and continue */