diff --git a/drb-frontend/types/leaflet.gridlayer.googlemutant.d.ts b/drb-frontend/types/leaflet.gridlayer.googlemutant.d.ts
new file mode 100644
index 0000000..e5d46de
--- /dev/null
+++ b/drb-frontend/types/leaflet.gridlayer.googlemutant.d.ts
@@ -0,0 +1,4 @@
+declare module "leaflet.gridlayer.googlemutant" {
+  // Side-effect import — augments L.gridLayer with googleMutant factory.
+  // No public API is consumed directly from this module.
+}