diff --git a/test/bfs_test.cc b/test/bfs_test.cc
--- a/test/bfs_test.cc
+++ b/test/bfs_test.cc
@@ -144,7 +144,7 @@
   Node s, t;
 
   std::istringstream input(test_lgf);
-  digraphReader(input, G).
+  digraphReader(G, input).
     node("source", s).
     node("target", t).
     run();