diff --git a/deli/kubernetes/resources/v1alpha1/volume/model.py b/deli/kubernetes/resources/v1alpha1/volume/model.py
index 273daa4..a902ce4 100644
--- a/deli/kubernetes/resources/v1alpha1/volume/model.py
+++ b/deli/kubernetes/resources/v1alpha1/volume/model.py
@@ -118,7 +118,7 @@ def attached_to(self):
     @attached_to.setter
     def attached_to(self, value):
         if value is None:
-            self._raw['metadata']['labels'][ATTACHED_TO_LABEL] = None
+            self._raw['metadata']['labels'][ATTACHED_TO_LABEL] = ""
         else:
             self._raw['metadata']['labels'][ATTACHED_TO_LABEL] = str(value.id)