diff --git a/freqtrade/strategy/strategy_helper.py b/freqtrade/strategy/strategy_helper.py
index 53f625001..aa753a829 100644
--- a/freqtrade/strategy/strategy_helper.py
+++ b/freqtrade/strategy/strategy_helper.py
@@ -55,17 +55,16 @@ def merge_informative_pair(dataframe: pd.DataFrame, informative: pd.DataFrame,
 
     # Rename columns to be unique
     date_merge = 'date_merge'
-    if append_timeframe and not suffix:
+    if suffix and append_timeframe:
+        raise ValueError("You can not specify `append_timeframe` as True and a `suffix`.")
+    elif append_timeframe:
         date_merge = f'date_merge_{timeframe_inf}'
         informative.columns = [f"{col}_{timeframe_inf}" for col in informative.columns]
 
-    elif suffix and not append_timeframe:
+    elif suffix:
         date_merge = f'date_merge_{suffix}'
         informative.columns = [f"{col}_{suffix}" for col in informative.columns]
 
-    elif suffix and append_timeframe:
-        raise ValueError("You can not specify `append_timeframe` as True and a `suffix`.")
-
     # Combine the 2 dataframes
     # all indicators on the informative sample MUST be calculated before this point
     if ffill: