diff --git a/pudu/perturbation.py b/pudu/perturbation.py
index a01e205..c1f6962 100644
--- a/pudu/perturbation.py
+++ b/pudu/perturbation.py
@@ -362,6 +362,23 @@ def apply(self, x, row, col, window, bias):
         return x, None
 
 
+class CustomSum:
+    """
+    Sums a custom vector as a perturbation to the array.
+
+    :type func: callable
+    :param func: A function that takes a single argument and returns a single value.
+
+    :rtype: 4d array
+    :return: Custom perturbated array
+    """
+    def __init__(self, custom):
+        self.custom = custom
+    def apply(self, x, row, col, window, bias):
+        x[0, row:row+window[0], col:col+window[1], 0] = x[0, row:row+window[0], col:col+window[1], 0] + self.custom[0, row:row+window[0], col:col+window[1], 0]
+        return x, None
+
+
 class UpperThreshold:
     """
     Sets values above a certain threshold to a specified value.