diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c5b8901..8a24e9b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3908,7 +3908,7 @@
 	EXT4_SB(sb)->s_journal = journal;
 	ext4_clear_journal_err(sb, es);
 
-	if (journal_devnum &&
+	if (!really_read_only && journal_devnum &&
 	    journal_devnum != le32_to_cpu(es->s_journal_dev)) {
 		es->s_journal_dev = cpu_to_le32(journal_devnum);