diff --git a/pypop7/benchmarks/base_functions.py b/pypop7/benchmarks/base_functions.py
index bd9e61c84..2b408e2ca 100644
--- a/pypop7/benchmarks/base_functions.py
+++ b/pypop7/benchmarks/base_functions.py
@@ -746,7 +746,7 @@ def __call__(self, x):
 def michalewicz(x):
     """**Michalewicz** test function.
 
-       .. note:: It's LaTeX formulation is `$f(x) = -\sum_{i = 1}^{n}\sin(x_i)(\sin(\frac{ix_i^2}{\pi}))^{20}$`.
+       .. note:: It's LaTeX formulation is `$-\sum_{i = 1}^{n}\sin(x_i)(\sin(\frac{ix_i^2}{\pi}))^{20}$`.
 
     Parameters
     ----------