Index: lib/libc/string/memcmp.3
===================================================================
--- lib/libc/string/memcmp.3
+++ lib/libc/string/memcmp.3
@@ -29,7 +29,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd August 15, 2016
+.Dd June 5, 2024
 .Dt MEMCMP 3
 .Os
 .Sh NAME
@@ -45,27 +45,25 @@
 The
 .Fn memcmp
 function
-compares byte string
+compares byte objdect
 .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 ,
Index: lib/libc/tests/string/memcmp_test.c
===================================================================
--- lib/libc/tests/string/memcmp_test.c
+++ lib/libc/tests/string/memcmp_test.c
@@ -41,14 +41,14 @@
 #endif
 
 /*
- * On FreeBSD we demand that memcmp returns the difference between the
- * characters at the first site of mismatch.  However, ISO/IEC 9899:1990
- * only specifies that a number greater than, equal to, or less than
- * zero shall be returned.  If a unit test for this less strict
- * behaviour is desired, define RES(x) to be (((x) > 0) - ((x) < 0)).
+ * On FreeBSD we previously demanded that memcmp returns the difference
+ * between the characters at the first site of mismatch.  However,
+ * ISO/IEC 9899:1990 only specifies that a number greater than, equal
+ * to, or less than zero shall be returned.  If a unit test for this
+ * more strict ehaviour is desired, define RES(x) to be (x).
  */
 #ifndef RES
-#define RES(x) (x)
+#define RES(x) (((x) > 0) - ((x) < 0))
 #endif
 
 static int (*memcmp_fn)(const void *, const void *, size_t);