diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c
index d971ba4ebe27..91f45ab99c89 100644
--- a/sys/kern/kern_shutdown.c
+++ b/sys/kern/kern_shutdown.c
@@ -50,6 +50,7 @@
 #include <sys/buf.h>
 #include <sys/conf.h>
 #include <sys/cons.h>
+#include <sys/disklabel.h>
 #include <sys/eventhandler.h>
 #include <sys/kernel.h>
 #include <sys/kthread.h>
@@ -429,8 +430,8 @@ setdumpdev(dev_t dev)
 	/*
 	 * XXX should clean up checking in dumpsys() to be more like this.
 	 */
-	newdumplo = psize - Maxmem * PAGE_SIZE / DEV_BSIZE;
-	if (newdumplo < 0)
+	newdumplo = psize - Maxmem * (PAGE_SIZE / DEV_BSIZE);
+	if (newdumplo <= LABELSECTOR)
 		return (ENOSPC);
 	dumpdev = dev;
 	dumplo = newdumplo;
diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index 2553bbcc2e18..da961bab3e6e 100644
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -154,8 +154,8 @@ disk_dumpcheck(dev_t dev, u_int *count, u_int *blkno, u_int *secsize)
 	dl = dsgetlabel(dev, dp->d_slice);
 	if (!dl)
 		return (ENXIO);
-	*count = (u_long)Maxmem * PAGE_SIZE / dl->d_secsize;
-	if (dumplo < 0 || 
+	*count = Maxmem * (PAGE_SIZE / dl->d_secsize);
+	if (dumplo <= LABELSECTOR || 
 	    (dumplo + *count > dl->d_partitions[dkpart(dev)].p_size))
 		return (EINVAL);
 	boff = dl->d_partitions[dkpart(dev)].p_offset +