diff --git a/supervised/preprocessing/text_transformer.py b/supervised/preprocessing/text_transformer.py
index ceda959c..b8b3be46 100644
--- a/supervised/preprocessing/text_transformer.py
+++ b/supervised/preprocessing/text_transformer.py
@@ -1,5 +1,5 @@
 import warnings
-
+import numpy as np
 import pandas as pd
 from sklearn.feature_extraction.text import TfidfVectorizer
 
@@ -70,4 +70,4 @@ def from_json(self, data_json):
             )
             self._vectorizer.vocabulary_ = vocabulary
             self._vectorizer.fixed_vocabulary_ = fixed_vocabulary
-            self._vectorizer.idf_ = idf
+            self._vectorizer.idf_ = np.array(idf)
diff --git a/tests/tests_preprocessing/test_text_transformer.py b/tests/tests_preprocessing/test_text_transformer.py
index 25191024..5ee385ea 100644
--- a/tests/tests_preprocessing/test_text_transformer.py
+++ b/tests/tests_preprocessing/test_text_transformer.py
@@ -23,6 +23,7 @@ def test_transformer(self):
         transf = TextTransformer()
         transf.fit(df, "col1")
         df = transf.transform(df)
+        
         self.assertTrue(df.shape[0] == 5)
         self.assertTrue("col1" not in df.columns)