diff --git a/designate/quota/base.py b/designate/quota/base.py
index 49a0be5be..6082123cd 100644
--- a/designate/quota/base.py
+++ b/designate/quota/base.py
@@ -73,7 +73,7 @@ class Quota(DriverPlugin, metaclass=abc.ABCMeta):
 
         if resource not in quotas:
             raise exceptions.QuotaResourceUnknown("%s is not a valid quota "
-                                                  "resource", resource)
+                                                  "resource" % resource)
 
         return quotas[resource]
 
diff --git a/designate/quota/impl_storage.py b/designate/quota/impl_storage.py
index 1b7ad0b7d..ab03b70bf 100644
--- a/designate/quota/impl_storage.py
+++ b/designate/quota/impl_storage.py
@@ -61,7 +61,7 @@ class StorageQuota(base.Quota):
 
         if resource not in list(self.get_default_quotas(context).keys()):
             raise exceptions.QuotaResourceUnknown("%s is not a valid quota "
-                                                  "resource", resource)
+                                                  "resource" % resource)
 
         try:
             self._create_quota(context, tenant_id, resource, hard_limit)