diff --git a/otc_metadata/services.py b/otc_metadata/services.py
index 76fd35f3..195b067e 100644
--- a/otc_metadata/services.py
+++ b/otc_metadata/services.py
@@ -216,7 +216,7 @@ class Services(object):
         :param str service_type: Filter by service_type
         """
         res = dict()
-        res["service"] = {}
+        res['service'] = {}
         docs = []
         services = self._service_data
         for doc in services['documents']: