diff --git a/sorts/radix_sort.py b/sorts/radix_sort.py
index 1dbf5fbd1365..7571826908bb 100644
--- a/sorts/radix_sort.py
+++ b/sorts/radix_sort.py
@@ -11,17 +11,27 @@
 
 def radix_sort(list_of_ints: list[int]) -> list[int]:
     """
-    Examples:
+    Sort a list of non-negative integers using radix sort.
+
+    This implementation works only with non-negative values because it
+    iterates over the decimal digits of each number.
+
     >>> radix_sort([0, 5, 3, 2, 2])
     [0, 2, 2, 3, 5]
-
     >>> radix_sort(list(range(15))) == sorted(range(15))
     True
-    >>> radix_sort(list(range(14,-1,-1))) == sorted(range(15))
+    >>> radix_sort(list(range(14, -1, -1))) == sorted(range(15))
     True
-    >>> radix_sort([1,100,10,1000]) == sorted([1,100,10,1000])
+    >>> radix_sort([1, 100, 10, 1000]) == sorted([1, 100, 10, 1000])
     True
+    >>> radix_sort([3, 1, -1, 2])
+    Traceback (most recent call last):
+    ...
+    ValueError: All numbers in list_of_ints must be non-negative
     """
+    if any(item < 0 for item in list_of_ints):
+        raise ValueError("All numbers in list_of_ints must be non-negative")
+
     placement = 1
     max_digit = max(list_of_ints)
     while placement <= max_digit: