diff --git a/.changeset/unlucky-chairs-accept.md b/.changeset/unlucky-chairs-accept.md
new file mode 100644
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@@ -0,0 +1,5 @@
+---
+'@backstage/test-utils': patch
+---
+
+Allow `ExternalRouteRef` bindings in `mountedRoutes` to work with the latest version of core-api.