diff --git a/automan/utils.py b/automan/utils.py
index 3beb946..2c7364c 100644
--- a/automan/utils.py
+++ b/automan/utils.py
@@ -179,6 +179,8 @@ def _key2name(k):
             return f'{r}_{v}'
         elif isinstance(v, str):
             return v
+        elif v is None:
+            return k
         else:
             return f'{k}_{v}'