diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b100b8dae588..46ecb7405af1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2716,7 +2716,7 @@ int open_ctree(struct super_block *sb,
 		~BTRFS_FEATURE_INCOMPAT_SUPP;
 	if (features) {
 		btrfs_err(fs_info,
-		    "cannot mount because of unsupported optional features (%llx)",
+		    "cannot mount because of unsupported optional features (0x%llx)",
 		    features);
 		err = -EINVAL;
 		goto fail_alloc;
@@ -2769,7 +2769,7 @@ int open_ctree(struct super_block *sb,
 		~BTRFS_FEATURE_COMPAT_RO_SUPP;
 	if (!(sb->s_flags & MS_RDONLY) && features) {
 		btrfs_err(fs_info,
-	"cannot mount read-write because of unsupported optional features (%llx)",
+	"cannot mount read-write because of unsupported optional features (0x%llx)",
 		       features);
 		err = -EINVAL;
 		goto fail_alloc;