diff --git a/libsecondlife-cs/NetworkManager.cs b/libsecondlife-cs/NetworkManager.cs
index 66f0e2d7..370841e6 100644
--- a/libsecondlife-cs/NetworkManager.cs
+++ b/libsecondlife-cs/NetworkManager.cs
@@ -361,6 +361,7 @@ namespace libsecondlife
 							Helpers.LogLevel.Info);
 
 						// Avoid firing a callback twice for the same packet
+                        InboxMutex.ReleaseMutex();
 						return;
 					}
 					else