diff --git a/toolchains/arduino/org.eclipse.cdt.arduino.core/src/org/eclipse/cdt/arduino/core/internal/board/LibraryIndex.java b/toolchains/arduino/org.eclipse.cdt.arduino.core/src/org/eclipse/cdt/arduino/core/internal/board/LibraryIndex.java
index 10ef898de35..75d1b69c9fc 100644
--- a/toolchains/arduino/org.eclipse.cdt.arduino.core/src/org/eclipse/cdt/arduino/core/internal/board/LibraryIndex.java
+++ b/toolchains/arduino/org.eclipse.cdt.arduino.core/src/org/eclipse/cdt/arduino/core/internal/board/LibraryIndex.java
@@ -13,6 +13,7 @@ import java.util.Set;
 public class LibraryIndex {
 
 	private List<ArduinoLibrary> libraries;
+	public static final String UNCATEGORIZED = "Uncategorized"; //$NON-NLS-1$
 
 	// category name to library name
 	private Map<String, Set<String>> categories = new HashMap<>();
@@ -25,7 +26,7 @@ public class LibraryIndex {
 
 			String category = library.getCategory();
 			if (category == null) {
-				category = "Uncategorized"; //$NON-NLS-1$
+				category = UNCATEGORIZED;
 			}
 
 			Set<String> categoryLibs = categories.get(category);
diff --git a/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/project/LibrariesPropertyPage.java b/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/project/LibrariesPropertyPage.java
index 879db2f6ee0..5c301a6f7fe 100644
--- a/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/project/LibrariesPropertyPage.java
+++ b/toolchains/arduino/org.eclipse.cdt.arduino.ui/src/org/eclipse/cdt/arduino/ui/internal/project/LibrariesPropertyPage.java
@@ -84,7 +84,7 @@ public class LibrariesPropertyPage extends PropertyPage {
 				} catch (CoreException e) {
 					Activator.log(e);
 				}
-				return null;
+				return LibraryIndex.UNCATEGORIZED;
 			} else if (element instanceof String || element instanceof ArduinoPlatform) {
 				return index;
 			} else {