diff --git a/platform/analysis-impl/src/com/intellij/psi/impl/source/resolve/reference/impl/providers/NullFileReferenceHelper.java b/platform/analysis-impl/src/com/intellij/psi/impl/source/resolve/reference/impl/providers/NullFileReferenceHelper.java
index c54d69f500db..3e18db1aff67 100644
--- a/platform/analysis-impl/src/com/intellij/psi/impl/source/resolve/reference/impl/providers/NullFileReferenceHelper.java
+++ b/platform/analysis-impl/src/com/intellij/psi/impl/source/resolve/reference/impl/providers/NullFileReferenceHelper.java
@@ -45,7 +45,7 @@ public class NullFileReferenceHelper extends FileReferenceHelper {
   @Override
   @NotNull
   public Collection<PsiFileSystemItem> getRoots(@NotNull final Module module) {
-    return ContainerUtil.map(ModuleRootManager.getInstance(module).getContentRoots(), new Function<VirtualFile, PsiFileSystemItem>() {
+    return ContainerUtil.mapNotNull(ModuleRootManager.getInstance(module).getContentRoots(), new Function<VirtualFile, PsiFileSystemItem>() {
       @Override
       public PsiFileSystemItem fun(VirtualFile virtualFile) {
         return PsiManager.getInstance(module.getProject()).findDirectory(virtualFile);