diff --git a/fedot/preprocessing/preprocessing.py b/fedot/preprocessing/preprocessing.py
index 0752e17b3e..144d865eef 100644
--- a/fedot/preprocessing/preprocessing.py
+++ b/fedot/preprocessing/preprocessing.py
@@ -568,7 +568,7 @@ def reduce_mem_usage_np(arr, initial_types):
                 col = col.astype(init_type)
                 col_type = col.dtype.name
 
-                if col_type not in ['object']:
+                if col_type not in ['object', 'str384']:
                     c_min = col.max()
                     c_max = col.max()