diff --git a/cpp/mwmatching.h b/cpp/mwmatching.h
index b32a9e3..6ae16dd 100644
--- a/cpp/mwmatching.h
+++ b/cpp/mwmatching.h
@@ -1342,8 +1342,8 @@ struct MatchingContext
 
         // Add all vertices inside the newly labeled S-blossom to the queue.
         for_vertices_in_blossom(bx,
-            [this](VertexId x) {
-                queue.push_back(x);
+            [this](VertexId v) {
+                queue.push_back(v);
             });
     }