diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index a156092f9..1ae025fca 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -3320,7 +3320,8 @@ category determines the month spellings.
 Sort numerically: the number begins each line; specifically, it consists
 of optional blanks, an optional @samp{-} sign, and zero or more
 digits possibly separated by thousands separators, optionally followed
-by a decimal-point character and zero or more digits.  The @env{LC_NUMERIC}
+by a decimal-point character and zero or more digits.  A string of
+zero digits is interpreted as @samp{0}.  The @env{LC_NUMERIC}
 locale specifies the decimal-point character and thousands separator.
 
 Numeric sort uses what might be considered an unconventional method to