diff --git a/Grow.c b/Grow.c
index 61347b7..1ab4fbc 100644
--- a/Grow.c
+++ b/Grow.c
@@ -657,7 +657,7 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
 				offsets[sd->role] = sd->offset;
 				if (fdlist[sd->role] < 0) {
 					fprintf(stderr, Name ": %s: cannot open component %s\n",
-						devname, dn);
+						devname, dn?dn:"-unknown-");
 					goto abort;
 				}
 			} else {
@@ -667,7 +667,7 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
 				offsets[d] = sd->offset;
 				if (fdlist[d]<0) {
 					fprintf(stderr, Name ": %s: cannot open component %s\n",
-						devname, dn);
+						devname, dn?dn:"-unknown");
 					goto abort;
 				}
 				d++;
diff --git a/config.c b/config.c
index 20dc725..157bdff 100644
--- a/config.c
+++ b/config.c
@@ -242,7 +242,8 @@ mddev_dev_t load_partitions(void)
 		minor = strtoul(mp, NULL, 10);
 
 		name = map_dev(major, minor, 1);
-
+		if (!name)
+			continue;
 		d = malloc(sizeof(*d));
 		d->devname = strdup(name);
 		d->next = rv;
diff --git a/util.c b/util.c
index d54d445..2cb6dd3 100644
--- a/util.c
+++ b/util.c
@@ -417,12 +417,9 @@ char *map_dev(int major, int minor, int create)
 	char *std = NULL, *nonstd=NULL;
 	int did_check = 0;
 
-	if (major == 0 && minor == 0) {
-		if (!create)
+	if (major == 0 && minor == 0)
 			return NULL;
-		else
-			return "0:0";
-	}
+
  retry:
 	if (!devlist_ready) {
 		char *dev = "/dev";
@@ -636,8 +633,12 @@ int dev_open(char *dev, int flags)
 	char *e;
 	int fd = -1;
 	char devname[32];
-	int major = strtoul(dev, &e, 0);
+	int major;
 	int minor;
+
+	if (!dev) return -1;
+
+	major = strtoul(dev, &e, 0);
 	if (e > dev && *e == ':' && e[1] &&
 	    (minor = strtoul(e+1, &e, 0)) >= 0 &&
 	    *e == 0) {