diff --git a/src/Xamarin.Android.Build.Tasks/Tasks/DetermineJavaLibrariesToCompile.cs b/src/Xamarin.Android.Build.Tasks/Tasks/DetermineJavaLibrariesToCompile.cs
index 36b88cf99c7..ed87c39eeff 100644
--- a/src/Xamarin.Android.Build.Tasks/Tasks/DetermineJavaLibrariesToCompile.cs
+++ b/src/Xamarin.Android.Build.Tasks/Tasks/DetermineJavaLibrariesToCompile.cs
@@ -65,7 +65,8 @@ public override bool Execute ()
 			jars          = jars.Where (j => distinct.Contains (j)).ToList ();
 
 			JavaLibrariesToCompile = jars.Where (j => !IsExcluded (j.ItemSpec)).ToArray ();
-			ReferenceJavaLibraries = jars.Except (JavaLibrariesToCompile).ToArray ();
+			ReferenceJavaLibraries = (ExternalJavaLibraries ?? Enumerable.Empty<ITaskItem> ())
+				.Concat (jars.Except (JavaLibrariesToCompile)).ToArray ();
 
 			Log.LogDebugTaskItems ("  JavaLibrariesToCompile:", JavaLibrariesToCompile);
 			Log.LogDebugTaskItems ("  ReferenceJavaLibraries:", ReferenceJavaLibraries);