diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index 8254d3f..d68cf11 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -186,7 +186,8 @@
 
 .. function:: log2(x)
 
-   Return the base-2 logarithm of *x*.
+   Return the base-2 logarithm of *x*. This is usually more accurate than
+   ``log(x, 2)``.
 
    .. versionadded:: 3.3