diff --git a/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/ProjectFileIndexImpl.java b/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/ProjectFileIndexImpl.java
index a9bfea4bc768..1fadbde8a58e 100644
--- a/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/ProjectFileIndexImpl.java
+++ b/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/ProjectFileIndexImpl.java
@@ -188,13 +188,14 @@ public class ProjectFileIndexImpl extends FileIndexBase implements ProjectFileIn
 
   @Override
   public boolean isInLibrarySource(@NotNull VirtualFile fileOrDir) {
-    return getInfoForFileOrDirectory(fileOrDir).isInLibrarySource();
+    DirectoryInfo info = getInfoForFileOrDirectory(fileOrDir);
+    return info.isInProject() && info.isInLibrarySource();
   }
 
   // a slightly faster implementation then the default one
   public boolean isInLibrary(@NotNull VirtualFile fileOrDir) {
     DirectoryInfo info = getInfoForFileOrDirectory(fileOrDir);
-    return info.isInProject() && info.hasLibraryClassRoot() || info.isInLibrarySource();
+    return info.isInProject() && (info.hasLibraryClassRoot() || info.isInLibrarySource());
   }
 
   @Override