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diff --git a/lib/libc/string/memcmp.3 b/lib/libc/string/memcmp.3
--- a/lib/libc/string/memcmp.3
+++ b/lib/libc/string/memcmp.3
@@ -29,12 +29,12 @@
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.Dd August 15, 2016
+.Dd November 20, 2024
.Dt MEMCMP 3
.Os
.Sh NAME
.Nm memcmp
-.Nd compare byte string
+.Nd compare bytes in memory
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
@@ -45,27 +45,25 @@
The
.Fn memcmp
function
-compares byte string
+compares byte object
.Fa b1
-against byte string
+against byte object
.Fa b2 .
-Both strings are assumed to be
+Both objects are assumed to be
.Fa len
bytes long.
.Sh RETURN VALUES
The
.Fn memcmp
-function
-returns zero if the two strings are identical,
-otherwise returns the difference between the first two differing bytes
-(treated as
-.Vt "unsigned char"
-values, so that
-.Sq Li \e200
-is greater than
-.Sq Li \&\e0 ,
-for example).
-Zero-length strings are always identical.
+function returns zero if the two objects are identical.
+Zero-length objects are considered identical.
+The
+.Fn memcmp
+function returns a negative value if the first differing byte has a lower
+value in
+.Fa b1
+and a positive value if the first differing byte has a higher value in
+.Fa b1 .
.Sh SEE ALSO
.Xr bcmp 3 ,
.Xr strcasecmp 3 ,
@@ -80,3 +78,14 @@
function
conforms to
.St -isoC .
+.Sh CAVEATS
+If the objects differ, the C library
+.Fn memcmp
+implementation returns the difference between the first two differing bytes
+.Po treated as
+.Vt "unsigned char"
+values
+.Pc .
+This behavior is not specified by
+.St -isoC ,
+is not portable, and may not occur in light of compiler optimizations.

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