diff --git a/src/servers/app/EventDispatcher.cpp b/src/servers/app/EventDispatcher.cpp
index b45f3c9298..9c8fb902f6 100644
--- a/src/servers/app/EventDispatcher.cpp
+++ b/src/servers/app/EventDispatcher.cpp
@@ -612,7 +612,8 @@ EventDispatcher::SetDragMessage(BMessage& message,
 
 	if (fLastButtons == 0) {
 		// mouse buttons has already been released or was never pressed
-		bitmap->ReleaseReference();
+		if (bitmap != NULL)
+			bitmap->ReleaseReference();
 		return;
 	}
 
diff --git a/src/servers/app/ServerWindow.cpp b/src/servers/app/ServerWindow.cpp
index 242438faf2..fef86d05c6 100644
--- a/src/servers/app/ServerWindow.cpp
+++ b/src/servers/app/ServerWindow.cpp
@@ -2074,7 +2074,8 @@ fDesktop->UnlockSingleWindow();
 						fDesktop->EventDispatcher().SetDragMessage(dragMessage,
 							bitmap, offset);
 fDesktop->LockSingleWindow();
-						bitmap->ReleaseReference();
+						if (bitmap != NULL)
+							bitmap->ReleaseReference();
 				}
 				delete[] buffer;
 			}