diff --git a/plugins/3MFReader/ThreeMFWorkspaceReader.py b/plugins/3MFReader/ThreeMFWorkspaceReader.py
index c1c78037dd..3250706b97 100644
--- a/plugins/3MFReader/ThreeMFWorkspaceReader.py
+++ b/plugins/3MFReader/ThreeMFWorkspaceReader.py
@@ -5,6 +5,7 @@ from UM.Workspace.WorkspaceReader import WorkspaceReader
 class ThreeMFWorkspaceReader(WorkspaceReader):
     def __init__(self):
         super().__init__()
+        self._supported_extensions = [".3mf"]
 
     def preRead(self, file_name):
         return WorkspaceReader.PreReadResult.accepted