diff --git a/usr.sbin/fdread/fdread.c b/usr.sbin/fdread/fdread.c
index 770f92d36cbb..f3c2d9147b9c 100644
--- a/usr.sbin/fdread/fdread.c
+++ b/usr.sbin/fdread/fdread.c
@@ -170,7 +170,7 @@ doread(int fd, FILE *of, const char *_devname)
 	secsize = 128 << fdt.secsize;
 	tracksize = fdt.sectrac * secsize;
 	mediasize = tracksize * fdt.tracks * fdt.heads;
-	if ((trackbuf = malloc(tracksize)) == 0)
+	if ((trackbuf = malloc(tracksize)) == NULL)
 		errx(EX_TEMPFAIL, "out of memory");
 
 	if (!quiet)
diff --git a/usr.sbin/fdread/fdutil.c b/usr.sbin/fdread/fdutil.c
index c66b0c11bc00..bdd295aedf85 100644
--- a/usr.sbin/fdread/fdutil.c
+++ b/usr.sbin/fdread/fdutil.c
@@ -200,10 +200,10 @@ parse_fmt(const char *s, enum fd_drivetype type,
 	*out = in;
 
 	for (i = 0;; i++) {
-		if (s == 0)
+		if (s == NULL)
 			break;
 
-		if ((cp = strchr(s, ',')) == 0) {
+		if ((cp = strchr(s, ',')) == NULL) {
 			s1 = strdup(s);
 			if (s1 == NULL)
 				abort();