diff --git a/easy/One_Hot_Encoding_of_Nominal_Values/One_Hot_Encoding_of_Nominal_Values.py b/easy/One_Hot_Encoding_of_Nominal_Values/One_Hot_Encoding_of_Nominal_Values.py
index d65c09a..c89a731 100644
--- a/easy/One_Hot_Encoding_of_Nominal_Values/One_Hot_Encoding_of_Nominal_Values.py
+++ b/easy/One_Hot_Encoding_of_Nominal_Values/One_Hot_Encoding_of_Nominal_Values.py
@@ -1,7 +1,7 @@
 import numpy as np
 
 
-def to_categorical(x, n_col=None):
+def to_categorical(x : np.ndarray, n_col=None):
     # Your code here
     pass