diff --git a/etna/models/deadline_ma.py b/etna/models/deadline_ma.py
index 64c288851..8549d4c68 100644
--- a/etna/models/deadline_ma.py
+++ b/etna/models/deadline_ma.py
@@ -186,7 +186,7 @@ def forecast(self, df: pd.DataFrame, prediction_size: int) -> np.ndarray:
         history = df_history["target"]
         history = history[history.index >= context_beginning]
         if np.any(history.isnull()):
-            raise ValueError("There are NaNs in a forecast context, forecast method required context to filled!")
+            raise ValueError("There are NaNs in a forecast context, forecast method requires context to be filled!")
 
         index = pd.date_range(start=context_beginning, end=df.index[-1], freq=self._freq)
         result_template = np.append(history.values, np.zeros(prediction_size))
diff --git a/etna/models/seasonal_ma.py b/etna/models/seasonal_ma.py
index 4b9ebc817..99fc8d588 100644
--- a/etna/models/seasonal_ma.py
+++ b/etna/models/seasonal_ma.py
@@ -93,7 +93,7 @@ def forecast(self, df: pd.DataFrame, prediction_size: int) -> np.ndarray:
 
         history = df["target"][-expected_length:-prediction_size]
         if np.any(history.isnull()):
-            raise ValueError("There are NaNs in a forecast context, forecast method required context to filled!")
+            raise ValueError("There are NaNs in a forecast context, forecast method requires context to be filled!")
 
         res = np.append(history, np.zeros(prediction_size))
         for i in range(self.shift, len(res)):