diff --git a/updownio/services/checks.py b/updownio/services/checks.py
index 4bae967..19ca803 100644
--- a/updownio/services/checks.py
+++ b/updownio/services/checks.py
@@ -28,7 +28,7 @@ def _build_disabled_locations(disabled_locations):
         if not isinstance(disabled_locations, (list, tuple)):
             return r
 
-        for x in enumerate(disabled_locations):
+        for i, x in enumerate(disabled_locations):
             if isinstance(x, str):
                 r.append(('disabled_locations[]', x))
 
@@ -41,7 +41,7 @@ def _build_recipients(recipients):
         if not isinstance(recipients, (list, tuple)):
             return r
 
-        for x in enumerate(recipients):
+        for i, x in enumerate(recipients):
             if isinstance(x, str):
                 r.append(('recipients[]', x))