diff --git a/Doc/library/cmath.rst b/Doc/library/cmath.rst
index 26518a0458fd81..b6d5dbee21dcd5 100644
--- a/Doc/library/cmath.rst
+++ b/Doc/library/cmath.rst
@@ -338,7 +338,7 @@ Constants
 .. data:: nan
 
    A floating-point "not a number" (NaN) value.  Equivalent to
-   ``float('nan')``.
+   ``float('nan')``. See also :data:`math.nan`.
 
    .. versionadded:: 3.6