diff --git a/freqtrade/constants.py b/freqtrade/constants.py
index d5ba00cd5..dd3c07e69 100644
--- a/freqtrade/constants.py
+++ b/freqtrade/constants.py
@@ -74,7 +74,7 @@ CONF_SCHEMA = {
             'pattern': UNLIMITED_STAKE_AMOUNT
         },
         'tradable_balance_ratio': {
-            'type': ['number'],
+            'type': 'number',
             'minimum': 0.1,
             'maximum': 1,
             'default': 0.99