diff --git a/sloth/gui/propertyeditor.py b/sloth/gui/propertyeditor.py
index 6b1ad1b..ae1556d 100644
--- a/sloth/gui/propertyeditor.py
+++ b/sloth/gui/propertyeditor.py
@@ -90,6 +90,7 @@ class DefaultAttributeHandler(QGroupBox, AbstractAttributeHandler):
         return self._defaults
 
     def addValue(self, v):
+        self._values.append(v)
         button = QPushButton(v, self)
         button.setFlat(True)
         button.setCheckable(True)