diff --git a/supervised/preprocessing/preprocessing_utils.py b/supervised/preprocessing/preprocessing_utils.py
index d4b43b83..7a84b71e 100644
--- a/supervised/preprocessing/preprocessing_utils.py
+++ b/supervised/preprocessing/preprocessing_utils.py
@@ -83,11 +83,11 @@ def is_scale_needed(x_org):
 
     @staticmethod
     def is_log_scale_needed(x_org):
-        x = np.array(x_org[~pd.isnull(x_org)])
+        x_full = np.array(x_org[~pd.isnull(x_org)])
         # first scale on raw data
-        x = preprocessing.scale(x)
+        x = preprocessing.scale(x_full)
         # second scale on log data
-        x_log = preprocessing.scale(np.log(x - np.min(x) + 1))
+        x_log = preprocessing.scale(np.log(x_full - np.min(x_full) + 1))
 
         # the old approach, let's check how new approach will work
         # original_skew = np.abs(stats.skew(x))