diff --git a/sum_of_digits_of_a_number.py b/sum_of_digits_of_a_number.py
index 64d62b281b7..f17fd6bcf41 100644
--- a/sum_of_digits_of_a_number.py
+++ b/sum_of_digits_of_a_number.py
@@ -13,6 +13,8 @@
     0
     >>> sum_of_digits(999)
     27
+    >>> sum_of_digits(-123)
+    6
 """
 
 import sys
@@ -49,8 +51,8 @@ def sum_of_digits(n: int) -> int:
     Compute the sum of the digits of an integer.
 
     Args:
-        n:Non-negative integer
-        If the integer is negative , it is converted to postive interger and assigned to same number
+        n: Non-negative integer.
+        If the integer is negative, it is converted to positive before computing the sum.
 
     Returns:
         Sum of digits of the number.
@@ -60,8 +62,10 @@ def sum_of_digits(n: int) -> int:
         6
         >>> sum_of_digits(405)
         9
+        >>> sum_of_digits(-789)
+        24
     """
-    n=abs(n)
+    n = abs(n)  # FIX: handle negative numbers
     total = 0
     while n > 0:
         # Add last digit and remove it from n