diff --git a/maths/elu_activation.py b/maths/elu_activation.py
index cc1631551..2f5ded173 100644
--- a/maths/elu_activation.py
+++ b/maths/elu_activation.py
@@ -9,9 +9,10 @@ https://en.wikipedia.org/wiki/Rectifier_(neural_networks)
 """
 
 import numpy as np
+from typing import TYPE_CHECKING
 
 
-def elu_activation(vector: np.array, alpha: float) -> np.array:
+def elu_activation(vector: np.ndarray, alpha: float) -> np.ndarray:
     """
          Implements the ELU activation function.
          Parameters: