diff --git a/napari_clusters_plotter/_plotter.py b/napari_clusters_plotter/_plotter.py
index cdb68677..f34ec351 100644
--- a/napari_clusters_plotter/_plotter.py
+++ b/napari_clusters_plotter/_plotter.py
@@ -102,8 +102,8 @@ def manual_clustering_method(inside):
 
             modifiers = QGuiApplication.keyboardModifiers()
             if modifiers == Qt.ShiftModifier and clustering_ID in features.keys():
-                features[clustering_ID].mask(
-                    inside, other=features[clustering_ID].max() + 1, inplace=True
+                features[clustering_ID] = features[clustering_ID].mask(
+                    inside, other=features[clustering_ID].max() + 1
                 )
             else:
                 features[clustering_ID] = inside.astype(int)