diff --git a/ChangeLog b/ChangeLog
index 1d93077dcd..51867920fc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2016-12-16  Joseph Myers  <joseph@codesourcery.com>
+
+	* manual/arith.texi (Math Error Reporting): Document that sNaN
+	arguments are not considered domain errors.
+
 2016-12-16  Zack Weinberg <zackw@panix.com>
 	    Florian Weimer <fweimer@redhat.com>
 	    Nick Mathewson <nickm@torproject.org>
diff --git a/manual/arith.texi b/manual/arith.texi
index 41ab577237..a20a4dec6c 100644
--- a/manual/arith.texi
+++ b/manual/arith.texi
@@ -939,6 +939,11 @@ guaranteed; it is intended that @theglibc{} should set it when the
 underflow is to an appropriately signed zero, but not necessarily for
 other underflows.
 
+When a math function has an argument that is a signaling NaN,
+@theglibc{} does not consider this a domain error, so @code{errno} is
+unchanged, but the invalid exception is still raised (except for a few
+functions that are specified to handle signaling NaNs differently).
+
 Some of the math functions are defined mathematically to result in a
 complex value over parts of their domains.  The most familiar example of
 this is taking the square root of a negative number.  The complex math