diff --git a/apps/src/shared/gamma/containers/tabs/reducer.tsx b/apps/src/shared/gamma/containers/tabs/reducer.tsx
index 7476165c5e..ce4110937f 100644
--- a/apps/src/shared/gamma/containers/tabs/reducer.tsx
+++ b/apps/src/shared/gamma/containers/tabs/reducer.tsx
@@ -150,7 +150,7 @@ function createTabRouteFromConfig(config: TabRouteConfig): TabRoute {
 
 export type TabsContainerStateInitArg = {
   routeConfigs: TabRouteConfig[];
-  defaultRouteName?: string;
+  defaultRouteName?: string | undefined;
 };
 
 export function determineInitialTabsContainerState(