diff --git a/Source/OpenTK/Input/Buttons.cs b/Source/OpenTK/Input/Buttons.cs
index 5d3889e7..878c738f 100644
--- a/Source/OpenTK/Input/Buttons.cs
+++ b/Source/OpenTK/Input/Buttons.cs
@@ -30,8 +30,9 @@ namespace OpenTK.Input
     /// <summary>
     /// Enumerates available buttons for a canonical <c>GamePad</c> device.
     /// </summary>
-	public enum Buttons
-	{
+    [Flags]
+    public enum Buttons
+    {
         /// <summary>
         /// DPad up direction button
         /// </summary>