diff --git a/ServerMessage.ts b/ServerMessage.ts
index 7a7d3e0..77e85c8 100644
--- a/ServerMessage.ts
+++ b/ServerMessage.ts
@@ -186,7 +186,7 @@ export function isDesiredNameMessage(obj: unknown): obj is DesiredNameMessage {
     return false;
   }
   if (
-    !Object.hasOwnProperty.call(obj, "desiredName") ||
+    Object.hasOwnProperty.call(obj, "desiredName") &&
     typeof (obj as ServerMessage & { desiredName: unknown }).desiredName !==
       "string"
   ) {