diff --git a/platform/lang-impl/src/com/intellij/ide/scriptingContext/ScriptingLibraryMappings.java b/platform/lang-impl/src/com/intellij/ide/scriptingContext/ScriptingLibraryMappings.java
index c796667b7a03..6cd16ced5954 100644
--- a/platform/lang-impl/src/com/intellij/ide/scriptingContext/ScriptingLibraryMappings.java
+++ b/platform/lang-impl/src/com/intellij/ide/scriptingContext/ScriptingLibraryMappings.java
@@ -91,18 +91,27 @@ public class ScriptingLibraryMappings extends LanguagePerFileMappings<ScriptingL
   }
 
   @Override
+  @Nullable
   public ScriptingLibraryTable.LibraryModel chosenToStored(VirtualFile file, ScriptingLibraryTable.LibraryModel value) {
     if (value instanceof CompoundLibrary) return value;
     CompoundLibrary compoundLib = file == null ? myProjectLibs : myCompoundLibMap.get(file);
-    if (compoundLib == null) {
-      compoundLib = new CompoundLibrary();
-      myCompoundLibMap.put(file, compoundLib);
-    }
     if (value == null) {
-      compoundLib.clearLibraries();
+      if (compoundLib != null) {
+        compoundLib.clearLibraries();
+        myCompoundLibMap.remove(file);
+        compoundLib = null;
+      }
     }
     else {
+      if (compoundLib == null) {
+        compoundLib = new CompoundLibrary();
+        myCompoundLibMap.put(file, compoundLib);
+      }
       compoundLib.toggleLibrary(value);
+      if (compoundLib.isEmpty()) {
+        myCompoundLibMap.remove(file);
+        compoundLib = null;
+      }
     }
     return compoundLib;
   }