diff --git a/inventory_provider/config.py b/inventory_provider/config.py
index f332f5bb2bdf60b66c99c231addf5f0c23fcc94e..93aaa3876744741023cba81cec4f8ab0b50a476b 100644
--- a/inventory_provider/config.py
+++ b/inventory_provider/config.py
@@ -163,7 +163,7 @@ CONFIG_SCHEMA = {
                 'nren': {'type': 'string'},
                 'isp': {
                     'type': 'string',
-                    'enum': ['Cogent', 'Telia', 'CenturyLink']
+                    'enum': ['Cogent', 'Telia', 'CenturyLink', 'GTT']
                 },
                 'hosts': {
                     'type': 'array',