diff --git a/src/Xamarin.Android.Build.Tasks/Tasks/CreateMultiDexMainDexClassList.cs b/src/Xamarin.Android.Build.Tasks/Tasks/CreateMultiDexMainDexClassList.cs
index 1ead40be35a..d7937d24d87 100644
--- a/src/Xamarin.Android.Build.Tasks/Tasks/CreateMultiDexMainDexClassList.cs
+++ b/src/Xamarin.Android.Build.Tasks/Tasks/CreateMultiDexMainDexClassList.cs
@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.IO;
+using System.Text;
 
 using Microsoft.Build.Utilities;
 using Microsoft.Build.Framework;
@@ -97,7 +98,7 @@ void GenerateMainDexListBuilderCommands(CommandLineBuilder cmd)
 			var enclosingDoubleQuote = OS.IsWindows ? "\"" : string.Empty;
 			var enclosingQuote = OS.IsWindows ? string.Empty : "'";
 			var jars = JavaLibraries.Select (i => i.ItemSpec).Concat (new string [] { Path.Combine (ClassesOutputDirectory, "..", "classes.zip") });
-			cmd.AppendSwitchIfNotNull ("-Djava.ext.dirs=", Path.Combine (AndroidSdkBuildToolsPath, "lib"));
+			cmd.AppendSwitchUnquotedIfNotNull ("-classpath ", "\"" + GetMainDexListBuilderClasspath () + "\"");
 			cmd.AppendSwitch ("com.android.multidex.MainDexListBuilder");
 			if (!string.IsNullOrWhiteSpace (ExtraArgs))
 				cmd.AppendSwitch (ExtraArgs);
@@ -108,6 +109,12 @@ void GenerateMainDexListBuilderCommands(CommandLineBuilder cmd)
 			writeOutputToKeepFile = true;
 		}
 
+		string GetMainDexListBuilderClasspath ()
+		{
+			var libdir      = Path.Combine (AndroidSdkBuildToolsPath, "lib");
+			return string.Join (Path.PathSeparator.ToString (), Directory.EnumerateFiles (libdir, "*.jar"));
+		}
+
 		protected override void LogEventsFromTextOutput (string singleLine, MessageImportance messageImportance)
 		{
 			var match = CodeErrorRegEx.Match (singleLine);