diff --git a/freqtrade/constants.py b/freqtrade/constants.py
index d5c23fe1d..fdbff886e 100644
--- a/freqtrade/constants.py
+++ b/freqtrade/constants.py
@@ -13,6 +13,7 @@ DEFAULT_DB_PROD_URL = 'sqlite:///tradesv3.sqlite'
 DEFAULT_DB_DRYRUN_URL = 'sqlite://'
 UNLIMITED_STAKE_AMOUNT = 'unlimited'
 REQUIRED_ORDERTYPES = ['buy', 'sell', 'stoploss']
+ORDERTYPE_POSSIBILITIES = ['limit', 'market']
 
 
 TICKER_INTERVAL_MINUTES = {
@@ -102,6 +103,15 @@ CONF_SCHEMA = {
                 'order_book_max': {'type': 'number', 'minimum': 1, 'maximum': 50}
             }
         },
+        'order_types': {
+            'type': 'object',
+            'properties': {
+                'buy': {'type': 'string', 'enum': ORDERTYPE_POSSIBILITIES},
+                'sell': {'type': 'string', 'enum': ORDERTYPE_POSSIBILITIES},
+                'stoploss': {'type': 'string', 'enum': ORDERTYPE_POSSIBILITIES}
+            },
+            'required': ['buy', 'sell', 'stoploss']
+        },
         'exchange': {'$ref': '#/definitions/exchange'},
         'edge': {'$ref': '#/definitions/edge'},
         'experimental': {