diff --git a/editor.settings.storage/src/org/netbeans/modules/editor/settings/storage/MimeTypesTracker.java b/editor.settings.storage/src/org/netbeans/modules/editor/settings/storage/MimeTypesTracker.java
--- a/editor.settings.storage/src/org/netbeans/modules/editor/settings/storage/MimeTypesTracker.java
+++ b/editor.settings.storage/src/org/netbeans/modules/editor/settings/storage/MimeTypesTracker.java
@@ -46,6 +46,7 @@
 import java.beans.PropertyChangeSupport;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -219,6 +220,8 @@
             rebuild();
         }
     });
+
+    private final Set<FileObject> jarda = new HashSet<FileObject>();
     
     private void rebuild() {
         PropertyChangeEvent event = null;
@@ -243,7 +246,7 @@
             if (isBaseFolder) {
                 // Clear the cache
                 newMimeTypes = new HashMap<String, String>();
-                
+                jarda.clear();
                 // Go through mime type types
                 FileObject [] types = folder.getChildren();
                 for(int i = 0; i < types.length; i++) {
@@ -251,6 +254,7 @@
                         continue;
                     }
 
+                    jarda.add(types[i]);
                     // Go through mime type subtypes
                     FileObject [] subTypes = types[i].getChildren();
                     for(int j = 0; j < subTypes.length; j++) {