diff --git a/MaterialDesignThemes.Wpf/SnackbarMessageQueue.cs b/MaterialDesignThemes.Wpf/SnackbarMessageQueue.cs
index 5110af6b44..c9679c58b7 100644
--- a/MaterialDesignThemes.Wpf/SnackbarMessageQueue.cs
+++ b/MaterialDesignThemes.Wpf/SnackbarMessageQueue.cs
@@ -384,6 +384,11 @@ private static Tuple<SnackbarMessage, MouseNotOverManagedWaitHandle> CreateAndSh
             {
                 if (++clickCount == 1)
                     DoActionCallback(messageQueueItem);
+
+                // Don't operate with eventWaitHandle if disposed/invalid
+                if (actionClickWaitHandle.SafeWaitHandle.IsInvalid || actionClickWaitHandle.SafeWaitHandle.IsClosed)
+                    return;
+
                 actionClickWaitHandle.Set();
             };
             snackbar.SetCurrentValue(Snackbar.MessageProperty, snackbarMessage);