diff --git a/doc/c-strtod.texi b/doc/c-strtod.texi
index a2082e7..1ed8877 100644
--- a/doc/c-strtod.texi
+++ b/doc/c-strtod.texi
@@ -11,7 +11,7 @@
 
 The @code{c-strtod} module contains a string to number (@samp{double})
 conversion function operating on single-byte character strings, that operates
-as if the locale encoding was ASCII.
+as if the locale was "C".
 (The "C" locale on many systems has the locale encoding "ASCII".)
 
 The function is:
@@ -19,5 +19,10 @@ The function is:
 extern double c_strtod (const char *string, char **endp);
 @end smallexample
 
-In particular, only a period @samp{.} is accepted as decimal point, even
-when the current locale's notion of decimal point is a comma @samp{,}.
+In particular, only a period @samp{.} is accepted as decimal point (even
+when the current locale's notion of decimal point is a comma @samp{,}),
+and no characters outside the basic character set are accepted.
+
+This function aborts via xalloc_die if it can't allocate memory.
+On platforms without @code{strtod_l}, it isn't safe for use in
+multi-threaded applications since it calls @code{setlocale}.