Fix markup.
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index be3b70b..3d29736 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -317,7 +317,7 @@
:exc:`OverflowError`, ``math.log(0L)`` may raise :exc:`ValueError` instead.
All functions return a quiet *NaN* if at least one of the args is *NaN*.
- Signaling *NaN*s raise an exception. The exception type still depends on the
+ Signaling *NaN*\s raise an exception. The exception type still depends on the
platform and libm implementation. It's usually :exc:`ValueError` for *EDOM*
and :exc:`OverflowError` for errno *ERANGE*.