diff --git a/app/game-frontend/src/components/main/MapViewer.vue b/app/game-frontend/src/components/main/MapViewer.vue
index 3061938e..0ba580a8 100644
--- a/app/game-frontend/src/components/main/MapViewer.vue
+++ b/app/game-frontend/src/components/main/MapViewer.vue
@@ -75,6 +75,7 @@ const props = withDefaults(
     {
         // Vue casts an absent Boolean prop to false unless undefined is an explicit default.
         detailMode: undefined,
+        selectedCityId: undefined,
     }
 );