diff --git a/common.rc b/common.rc
index b50c695f8..e00d0183c 100644
--- a/common.rc
+++ b/common.rc
@@ -313,9 +313,10 @@ _scratch_mkfs()
     zfs)
 	# SCRATCH_DEV must be of the form 'pool/dataset'
 	/sbin/zfs list -H $SCRATCH_DEV > /dev/null 2>&1
-	if [ "$?" != "0" ]; then
-	    /sbin/zfs create -o mountpoint=legacy $SCRATCH_DEV
+	if [ "$?" = "0" ]; then
+            /sbin/zfs destroy -f $SCRATCH_DEV
 	fi
+	/sbin/zfs create -o mountpoint=legacy $SCRATCH_DEV
 	;;
     *)
 	/sbin/mkfs -t $FSTYP -- $MKFS_OPTIONS $* $SCRATCH_DEV
@@ -343,12 +344,12 @@ _scratch_mkfs_sized()
 	/sbin/mkfs.$FSTYP $MKFS_OPTIONS $SCRATCH_DEV -b $fssize
 	;;
     zfs)
-	# No size required due to the nature of pooled storage
 	# SCRATCH_DEV must be of the form 'pool/dataset'
 	/sbin/zfs list -H $SCRATCH_DEV > /dev/null 2>&1
-	if [ "$?" != "0" ]; then
-	    /sbin/zfs create -o mountpoint=legacy $SCRATCH_DEV
+	if [ "$?" = "0" ]; then
+            /sbin/zfs destroy -f $SCRATCH_DEV
 	fi
+	/sbin/zfs create -o mountpoint=legacy -o refquota=$fssize $SCRATCH_DEV
 	;;
     *)
 	_notrun "Filesystem $FSTYP not supported in _scratch_mkfs_sized"