diff --git a/dumux/freeflow/rans/problem.hh b/dumux/freeflow/rans/problem.hh
index 02d7a597b1c3b32c42f0fb307c770594e15f0594..4a16c81fc1379cb6a177b0c50caf950e0da3cff4 100644
--- a/dumux/freeflow/rans/problem.hh
+++ b/dumux/freeflow/rans/problem.hh
@@ -112,6 +112,10 @@ public:
         {
             for (const auto& intersection : intersections(gridView, element))
             {
+                // only search for walls at a global boundary
+                if (!intersection.boundary())
+                    continue;
+
                 GlobalPosition global = intersection.geometry().center();
                 if (asImp_().isOnWall(global))
                 {