diff --git a/buildman/manager/ephemeral.py b/buildman/manager/ephemeral.py
index b3e8c78e0..9e8c30f57 100644
--- a/buildman/manager/ephemeral.py
+++ b/buildman/manager/ephemeral.py
@@ -357,7 +357,7 @@ class EphemeralBuilderManager(BaseManager):
     self._watch_etcd(self._etcd_realm_prefix, self._handle_realm_change,
                      restarter=self._register_existing_realms)
 
-    self._etcd_cancel_build_prefix = self._manager_config('ETCD_CANCEL_PREFIX', 'cancel/')
+    self._etcd_cancel_build_prefix = self._manager_config.get('ETCD_CANCEL_PREFIX', 'cancel/')
     self._watch_etcd(self._etcd_cancel_build_prefix, self._cancel_build)
 
     self._etcd_lock_prefix = self._manager_config.get('ETCD_LOCK_PREFIX', 'lock/')