diff --git a/plugins/3MFWriter/ThreeMFWriter.py b/plugins/3MFWriter/ThreeMFWriter.py
index 6fd03361b7..42b03835dc 100644
--- a/plugins/3MFWriter/ThreeMFWriter.py
+++ b/plugins/3MFWriter/ThreeMFWriter.py
@@ -234,7 +234,7 @@ class ThreeMFWriter(MeshWriter):
         return True
 
     @call_on_qt_thread  # must be called from the main thread because of OpenGL
-    def _createSnapshot(self) -> None:
+    def _createSnapshot(self) -> Optional[Snapshot.snapshot]:
         Logger.log("d", "Creating thumbnail image...")
         if not CuraApplication.getInstance().isVisible:
             Logger.log("w", "Can't create snapshot when renderer not initialized.")