diff --git a/freqtrade/exchange/__init__.py b/freqtrade/exchange/__init__.py
index 23305b59f..d87d3fc85 100644
--- a/freqtrade/exchange/__init__.py
+++ b/freqtrade/exchange/__init__.py
@@ -135,9 +135,10 @@ class Exchange(object):
         """
         Checks if ticker interval from config is a supported timeframe on the exchange
         """
-        timeframes=self._api.timeframes
+        timeframes = self._api.timeframes
         if timeframe not in timeframes:
-            raise OperationalException(f'Invalid ticker {timeframe}, this Exchange supports {timeframes}')
+            raise OperationalException(
+                f'Invalid ticker {timeframe}, this Exchange supports {timeframes}')
 
     def exchange_has(self, endpoint: str) -> bool:
         """