diff --git a/tests/btrfs/012 b/tests/btrfs/012
index b39dec0c..cbd3882e 100755
--- a/tests/btrfs/012
+++ b/tests/btrfs/012
@@ -63,8 +63,10 @@ _require_command "$E2FSCK_PROG" e2fsck
 
 rm -f $seqres.full
 
+BLOCK_SIZE=`get_block_size $TEST_DIR`
+
 # Create & populate an ext4 filesystem
-$MKFS_EXT4_PROG -F -b 4096 $SCRATCH_DEV > $seqres.full 2>&1 || \
+$MKFS_EXT4_PROG -F -b $BLOCK_SIZE $SCRATCH_DEV > $seqres.full 2>&1 || \
 	_notrun "Could not create ext4 filesystem"
 # Manual mount so we don't use -t btrfs or selinux context
 mount -t ext4 $SCRATCH_DEV $SCRATCH_MNT