diff --git a/Lib/defconAppKit/controls/glyphView.py b/Lib/defconAppKit/controls/glyphView.py
index 1263eb4..0953385 100644
--- a/Lib/defconAppKit/controls/glyphView.py
+++ b/Lib/defconAppKit/controls/glyphView.py
@@ -415,7 +415,7 @@ def _populatePlacard(self):
                 if len(layerSet.layerOrder) > 1:
                     items.append(NSMenuItem.separatorItem())
                     # prep the state dictionary
-                    for layerName in self._placardLayerOptions.keys():
+                    for layerName in list(self._placardLayerOptions.keys()):
                         if layerName not in layerSet:
                             del self._placardLayerOptions[layerName]
                     for layerName in layerSet.layerOrder: