diff --git a/tests/generic/306 b/tests/generic/306
index e8e0fc0a..f45d1427 100644
--- a/tests/generic/306
+++ b/tests/generic/306
@@ -73,9 +73,9 @@ _scratch_mount -o ro || _fail "Could not mount scratch readonly"
 echo "== try to create new file"
 touch $SCRATCH_MNT/this_should_fail 2>&1 | _filter_scratch
 echo "== pwrite to null device"
-$XFS_IO_PROG -F -c "pwrite 0 512" /dev/null | _filter_xfs_io
+$XFS_IO_PROG -F -c "pwrite 0 512" $DEVNULL | _filter_xfs_io
 echo "== pread from zero device"
-$XFS_IO_PROG -F -c "pread 0 512" /dev/zero | _filter_xfs_io
+$XFS_IO_PROG -F -c "pread 0 512" $DEVZERO | _filter_xfs_io
 
 echo "== truncating write to null device"
 echo foo > $DEVNULL 2>&1 | _filter_scratch