diff --git a/arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java b/arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java
index a09eb2a468f..d430e7196e7 100644
--- a/arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java
+++ b/arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java
@@ -102,8 +102,14 @@ private void parseIndex(File file) throws IOException {
   }
 
   public void setLibrariesFolders(List<File> _librariesFolders) {
-    librariesFolders = _librariesFolders;
-    rescanLibraries();
+    if (librariesFolders != _librariesFolders && !librariesFolders.equals(_librariesFolders)) {
+      librariesFolders = _librariesFolders;
+      rescanLibraries();
+    }
+  }
+
+  public List<File> getLibrariesFolders() {
+    return librariesFolders;
   }
 
   public void rescanLibraries() {
diff --git a/arduino-core/src/processing/app/BaseNoGui.java b/arduino-core/src/processing/app/BaseNoGui.java
index 62cfd0d687c..1a895e89ea9 100644
--- a/arduino-core/src/processing/app/BaseNoGui.java
+++ b/arduino-core/src/processing/app/BaseNoGui.java
@@ -87,7 +87,7 @@ public class BaseNoGui {
   public static Map<String, LibraryList> importToLibraryTable;
 
   // XXX: Remove this field
-  static private List<File> librariesFolders;
+  static private ArrayList<File> librariesFolders;
 
   static UserNotifier notifier = new BasicUserNotifier();
 
@@ -245,7 +245,7 @@ static public String getHardwarePath() {
     return getHardwareFolder().getAbsolutePath();
   }
 
-  static public List<File> getLibrariesPath() {
+  static public ArrayList<File> getLibrariesPath() {
     return librariesFolders;
   }
 
@@ -680,7 +680,6 @@ static public void onBoardOrPortChange() {
     // other libraries with the same name.
     librariesIndexer.setSketchbookLibrariesFolder(getSketchbookLibrariesFolder());
     librariesIndexer.setLibrariesFolders(librariesFolders);
-    librariesIndexer.rescanLibraries();
 
     populateImportToLibraryTable();
   }