diff --git a/plugins/hg4idea/src/org/zmlx/hg4idea/ui/HgMergeDialog.java b/plugins/hg4idea/src/org/zmlx/hg4idea/ui/HgMergeDialog.java
index e2b2a82678a6..3d1d1932bc26 100644
--- a/plugins/hg4idea/src/org/zmlx/hg4idea/ui/HgMergeDialog.java
+++ b/plugins/hg4idea/src/org/zmlx/hg4idea/ui/HgMergeDialog.java
@@ -118,7 +118,7 @@ public class HgMergeDialog extends DialogWrapper {
   }
 
   private void loadBranches(VirtualFile root) {
-    assert branchesForRepos.get(root) != null;
+    assert branchesForRepos.get(root) != null : "No inforamtion about root " + root;
     branchSelector.setModel(new DefaultComboBoxModel(branchesForRepos.get(root).toArray()));
   }