diff --git a/src/maasserver/preseed_network.py b/src/maasserver/preseed_network.py
index 3851424fc..8bfa90e7d 100644
--- a/src/maasserver/preseed_network.py
+++ b/src/maasserver/preseed_network.py
@@ -309,7 +309,7 @@ class InterfaceConfiguration:
 
     def _get_matching_routes(self, source):
         """Return all route objects matching `source`."""
-        return {route for route in self.routes if route.source == source}
+        return {route for route in self.routes if str(route.source.cidr) == str(source.cidr)}
 
     def _generate_addresses(self, version=1):
         """Generate the various addresses needed for this interface."""