diff --git a/platform/lang-api/src/com/intellij/facet/FacetFinder.java b/platform/lang-api/src/com/intellij/facet/FacetFinder.java
index 10d6d627c112..0a9d5e5d168f 100644
--- a/platform/lang-api/src/com/intellij/facet/FacetFinder.java
+++ b/platform/lang-api/src/com/intellij/facet/FacetFinder.java
@@ -24,5 +24,6 @@ public abstract class FacetFinder {
   @NotNull
   public abstract <F extends Facet<?> & FacetRootsProvider> Collection<F> findFacets(VirtualFile file, FacetTypeId<F> type);
 
+  @NotNull
   public abstract <F extends Facet<?>> ModificationTracker getAllFacetsOfTypeModificationTracker(FacetTypeId<F> type);
 }
diff --git a/platform/lang-impl/src/com/intellij/facet/impl/FacetFinderImpl.java b/platform/lang-impl/src/com/intellij/facet/impl/FacetFinderImpl.java
index 9741dfdb0814..9222b909680c 100644
--- a/platform/lang-impl/src/com/intellij/facet/impl/FacetFinderImpl.java
+++ b/platform/lang-impl/src/com/intellij/facet/impl/FacetFinderImpl.java
@@ -52,7 +52,7 @@ public class FacetFinderImpl extends FacetFinder {
   }
 
   @Override
-  public <F extends Facet<?>> ModificationTracker getAllFacetsOfTypeModificationTracker(FacetTypeId<F> type) {
+  public <F extends Facet<?>> @NotNull ModificationTracker getAllFacetsOfTypeModificationTracker(FacetTypeId<F> type) {
     AllFacetsOfTypeModificationTracker tracker = myAllFacetTrackers.get(type);
     if (tracker == null) {
       tracker = new AllFacetsOfTypeModificationTracker<>(myProject, type);