diff --git a/platform/vcs-log/impl/src/com/intellij/vcs/log/data/RefsModel.java b/platform/vcs-log/impl/src/com/intellij/vcs/log/data/RefsModel.java
index 572a5f5be1d3..0f086ec78d5f 100644
--- a/platform/vcs-log/impl/src/com/intellij/vcs/log/data/RefsModel.java
+++ b/platform/vcs-log/impl/src/com/intellij/vcs/log/data/RefsModel.java
@@ -51,6 +51,7 @@ public class RefsModel implements VcsLogRefs {
     myRootsToHeadIndices = prepareRootsMap(heads, hashMap);
   }
 
+  @NotNull
   private static TIntObjectHashMap<VirtualFile> prepareRootsMap(@NotNull Set<Integer> heads, @NotNull VcsLogHashMap hashMap) {
     TIntObjectHashMap<VirtualFile> map = new TIntObjectHashMap<VirtualFile>();
     for (Integer head : heads) {