diff --git a/gamedata.cpp b/gamedata.cpp
index 2038cf0..485fa62 100644
--- a/gamedata.cpp
+++ b/gamedata.cpp
@@ -125,8 +125,7 @@ float GameData::calculate_strength(Vertex* node)
     list<Vertex*> visited;
 
     // Special case - a one-node tree just returns its own score!
-    list<Vertex*> all_nodes = get_colour(node->colour);
-    if (all_nodes.size() == 1) return (float)node->score;
+    if (node->neighbors.empty()) return (float)node->score;
 
     return calculate_strength_r(node, 0, visited);
 }