2 files changed, 3 insertions, 2 deletions

diff --git a/lib/libc/string/strcmp.c b/lib/libc/string/strcmp.c
index 79cfaa831b29..cf25e504b2d8 100644
--- a/lib/libc/string/strcmp.c
+++ b/lib/libc/string/strcmp.c
@@ -51,5 +51,5 @@ strcmp(s1, s2)
 	while (*s1 == *s2++)
 		if (*s1++ == 0)
 			return (0);
-	return (*(unsigned char *)s1 - *(unsigned char *)--s2);
+	return (*(const unsigned char *)s1 - *(const unsigned char *)(s2 - 1));
 }
diff --git a/lib/libc/string/strncmp.c b/lib/libc/string/strncmp.c
index 805b5b029688..4b701a9a385d 100644
--- a/lib/libc/string/strncmp.c
+++ b/lib/libc/string/strncmp.c
@@ -48,7 +48,8 @@ strncmp(s1, s2, n)
 		return (0);
 	do {
 		if (*s1 != *s2++)
-			return (*(unsigned char *)s1 - *(unsigned char *)--s2);
+			return (*(const unsigned char *)s1 -
+				*(const unsigned char *)(s2 - 1));
 		if (*s1++ == 0)
 			break;
 	} while (--n != 0);