diff --git a/maths/abs.py b/maths/abs.py
index 68c99a1d5..dfea52dfb 100644
--- a/maths/abs.py
+++ b/maths/abs.py
@@ -1,7 +1,7 @@
 """Absolute Value."""
 
 
-def abs_val(num):
+def abs_val(num: float) -> float:
     """
     Find the absolute value of a number.