diff --git a/plugins/3MFWriter/ThreeMFWorkspaceWriter.py b/plugins/3MFWriter/ThreeMFWorkspaceWriter.py
index eb0ecf5ed5..cff938788b 100644
--- a/plugins/3MFWriter/ThreeMFWorkspaceWriter.py
+++ b/plugins/3MFWriter/ThreeMFWorkspaceWriter.py
@@ -1,6 +1,8 @@
 # Copyright (c) 2020 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
+from typing import Optional
+
 import configparser
 from io import StringIO
 from threading import Lock
@@ -25,10 +27,9 @@ USER_SETTINGS_PATH = "Cura/user-settings.json"
 class ThreeMFWorkspaceWriter(WorkspaceWriter):
     def __init__(self):
         super().__init__()
-        self._ucp_model = None
-        self._is_ucp = False
+        self._ucp_model: Optional[SettingsExportModel] = None
 
-    def setExportModel(self, model):
+    def setExportModel(self, model: SettingsExportModel) -> None:
         if self._ucp_model != model:
             self._ucp_model = model
 
diff --git a/plugins/3MFWriter/ThreeMFWriter.py b/plugins/3MFWriter/ThreeMFWriter.py
index e60aae8dd9..6e3dc86890 100644
--- a/plugins/3MFWriter/ThreeMFWriter.py
+++ b/plugins/3MFWriter/ThreeMFWriter.py
@@ -61,7 +61,6 @@ class ThreeMFWriter(MeshWriter):
         self._unit_matrix_string = ThreeMFWriter._convertMatrixToString(Matrix())
         self._archive: Optional[zipfile.ZipFile] = None
         self._store_archive = False
-        self._is_ucp = False
 
     @staticmethod
     def _convertMatrixToString(matrix):
@@ -436,6 +435,5 @@ class ThreeMFWriter(MeshWriter):
         return extra_settings
 
     def exportUcp(self):
-        self._is_ucp = True
         self._config_dialog = UCPDialog()
         self._config_dialog.show()