diff --git a/chunk-recover.c b/chunk-recover.c
index 6c6db115..bcde39e2 100644
--- a/chunk-recover.c
+++ b/chunk-recover.c
@@ -743,7 +743,7 @@ static int scan_one_device(struct recover_control *rc, int fd,
 			break;
 
 		if (memcmp_extent_buffer(buf, rc->fs_devices->fsid,
-					 (unsigned long)btrfs_header_fsid(),
+					 btrfs_header_fsid(),
 					 BTRFS_FSID_SIZE)) {
 			bytenr += rc->sectorsize;
 			continue;
@@ -1044,8 +1044,7 @@ static int __rebuild_chunk_root(struct btrfs_trans_handle *trans,
 	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 	btrfs_set_header_owner(cow, BTRFS_CHUNK_TREE_OBJECTID);
 	write_extent_buffer(cow, root->fs_info->fsid,
-			(unsigned long)btrfs_header_fsid(),
-			BTRFS_FSID_SIZE);
+			btrfs_header_fsid(), BTRFS_FSID_SIZE);
 
 	write_extent_buffer(cow, root->fs_info->chunk_tree_uuid,
 			(unsigned long)btrfs_header_chunk_tree_uuid(cow),
diff --git a/cmds-check.c b/cmds-check.c
index e08b79d1..c4530f72 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -5597,8 +5597,7 @@ init:
 	btrfs_set_header_owner(c, root->root_key.objectid);
 
 	write_extent_buffer(c, root->fs_info->fsid,
-			    (unsigned long)btrfs_header_fsid(),
-			    BTRFS_FSID_SIZE);
+			    btrfs_header_fsid(), BTRFS_FSID_SIZE);
 
 	write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
 			    (unsigned long)btrfs_header_chunk_tree_uuid(c),
diff --git a/cmds-chunk.c b/cmds-chunk.c
index e06881b9..4c2f3ed1 100644
--- a/cmds-chunk.c
+++ b/cmds-chunk.c
@@ -744,8 +744,7 @@ static int scan_one_device(struct recover_control *rc, int fd,
 			break;
 
 		if (memcmp_extent_buffer(buf, rc->fs_devices->fsid,
-					 (unsigned long)btrfs_header_fsid(),
-					 BTRFS_FSID_SIZE)) {
+					 btrfs_header_fsid(), BTRFS_FSID_SIZE)) {
 			bytenr += rc->sectorsize;
 			continue;
 		}
@@ -1047,8 +1046,7 @@ static int __rebuild_chunk_root(struct btrfs_trans_handle *trans,
 	btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 	btrfs_set_header_owner(cow, BTRFS_CHUNK_TREE_OBJECTID);
 	write_extent_buffer(cow, root->fs_info->fsid,
-			(unsigned long)btrfs_header_fsid(),
-			BTRFS_FSID_SIZE);
+			btrfs_header_fsid(), BTRFS_FSID_SIZE);
 
 	write_extent_buffer(cow, root->fs_info->chunk_tree_uuid,
 			(unsigned long)btrfs_header_chunk_tree_uuid(cow),
diff --git a/ctree.c b/ctree.c
index 8efe1ed4..b54554bc 100644
--- a/ctree.c
+++ b/ctree.c
@@ -118,8 +118,7 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
 		btrfs_set_header_owner(cow, new_root_objectid);
 
 	write_extent_buffer(cow, root->fs_info->fsid,
-			    (unsigned long)btrfs_header_fsid(),
-			    BTRFS_FSID_SIZE);
+			    btrfs_header_fsid(), BTRFS_FSID_SIZE);
 
 	WARN_ON(btrfs_header_generation(buf) > trans->transid);
 	ret = btrfs_inc_ref(trans, new_root, cow, 0);
@@ -292,8 +291,7 @@ int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 		btrfs_set_header_owner(cow, root->root_key.objectid);
 
 	write_extent_buffer(cow, root->fs_info->fsid,
-			    (unsigned long)btrfs_header_fsid(),
-			    BTRFS_FSID_SIZE);
+			    btrfs_header_fsid(), BTRFS_FSID_SIZE);
 
 	WARN_ON(btrfs_header_generation(buf) > trans->transid);
 
@@ -1338,8 +1336,7 @@ static int noinline insert_new_root(struct btrfs_trans_handle *trans,
 	btrfs_set_header_owner(c, root->root_key.objectid);
 
 	write_extent_buffer(c, root->fs_info->fsid,
-			    (unsigned long)btrfs_header_fsid(),
-			    BTRFS_FSID_SIZE);
+			    btrfs_header_fsid(), BTRFS_FSID_SIZE);
 
 	write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
 			    (unsigned long)btrfs_header_chunk_tree_uuid(c),
@@ -1459,8 +1456,7 @@ static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
 	btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
 	btrfs_set_header_owner(split, root->root_key.objectid);
 	write_extent_buffer(split, root->fs_info->fsid,
-			    (unsigned long)btrfs_header_fsid(),
-			    BTRFS_FSID_SIZE);
+			    btrfs_header_fsid(), BTRFS_FSID_SIZE);
 	write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
 			    (unsigned long)btrfs_header_chunk_tree_uuid(split),
 			    BTRFS_UUID_SIZE);
@@ -2020,8 +2016,7 @@ again:
 	btrfs_set_header_owner(right, root->root_key.objectid);
 	btrfs_set_header_level(right, 0);
 	write_extent_buffer(right, root->fs_info->fsid,
-			    (unsigned long)btrfs_header_fsid(),
-			    BTRFS_FSID_SIZE);
+			    btrfs_header_fsid(), BTRFS_FSID_SIZE);
 
 	write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
 			    (unsigned long)btrfs_header_chunk_tree_uuid(right),
diff --git a/ctree.h b/ctree.h
index 499fea3b..4e84a8f5 100644
--- a/ctree.h
+++ b/ctree.h
@@ -1777,10 +1777,9 @@ static inline void btrfs_set_header_backref_rev(struct extent_buffer *eb,
 	btrfs_set_header_flags(eb, flags);
 }
 
-static inline u8 *btrfs_header_fsid(void)
+static inline unsigned long btrfs_header_fsid(void)
 {
-	unsigned long ptr = offsetof(struct btrfs_header, fsid);
-	return (u8 *)ptr;
+	return offsetof(struct btrfs_header, fsid);
 }
 
 static inline u8 *btrfs_header_chunk_tree_uuid(struct extent_buffer *eb)
diff --git a/disk-io.c b/disk-io.c
index f0d70406..5f3f4847 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -50,7 +50,7 @@ static int check_tree_block(struct btrfs_root *root, struct extent_buffer *buf)
 	fs_devices = root->fs_info->fs_devices;
 	while (fs_devices) {
 		if (!memcmp_extent_buffer(buf, fs_devices->fsid,
-					  (unsigned long)btrfs_header_fsid(),
+					  btrfs_header_fsid(),
 					  BTRFS_FSID_SIZE)) {
 			ret = 0;
 			break;
diff --git a/print-tree.c b/print-tree.c
index b54a067d..76037fe1 100644
--- a/print-tree.c
+++ b/print-tree.c
@@ -191,7 +191,7 @@ static void print_uuids(struct extent_buffer *eb)
 	char chunk_uuid[37];
 	u8 disk_uuid[BTRFS_UUID_SIZE];
 
-	read_extent_buffer(eb, disk_uuid, (unsigned long)btrfs_header_fsid(),
+	read_extent_buffer(eb, disk_uuid, btrfs_header_fsid(),
 			   BTRFS_FSID_SIZE);
 
 	fs_uuid[36] = '\0';
diff --git a/utils.c b/utils.c
index c6022fc0..accecefb 100644
--- a/utils.c
+++ b/utils.c
@@ -136,8 +136,8 @@ int make_btrfs(int fd, const char *device, const char *label,
 	btrfs_set_header_generation(buf, 1);
 	btrfs_set_header_backref_rev(buf, BTRFS_MIXED_BACKREF_REV);
 	btrfs_set_header_owner(buf, BTRFS_ROOT_TREE_OBJECTID);
-	write_extent_buffer(buf, super.fsid, (unsigned long)
-			    btrfs_header_fsid(), BTRFS_FSID_SIZE);
+	write_extent_buffer(buf, super.fsid, btrfs_header_fsid(),
+			    BTRFS_FSID_SIZE);
 
 	write_extent_buffer(buf, chunk_tree_uuid, (unsigned long)
 			    btrfs_header_chunk_tree_uuid(buf),