diff --git a/fastapi_versioning/versioning.py b/fastapi_versioning/versioning.py
index 0f282d2..1711758 100644
--- a/fastapi_versioning/versioning.py
+++ b/fastapi_versioning/versioning.py
@@ -40,8 +40,10 @@ def VersionedFastAPI(
     version_route_mapping: Dict[Tuple[int, int], List[APIRoute]] = defaultdict(
         list
     )
+    # Filter out non-APIRoute entries (e.g. _IncludedRouter from Starlette >=1.3.1)
+    api_routes = [r for r in app.routes if isinstance(r, APIRoute)]
     version_routes = [
-        version_to_route(route, default_version) for route in app.routes
+        version_to_route(route, default_version) for route in api_routes
     ]
 
     for version, route in version_routes: