diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 99ed9228a677..2772675bd35a 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -249,13 +249,13 @@ static inline unsigned char fat_checksum(const __u8 *name)
 	return s;
 }
 
-static inline sector_t fat_clus_to_blknr(struct msdos_sb_info *sbi, int clus)
+static inline sector_t fat_clus_to_blknr(const struct msdos_sb_info *sbi, int clus)
 {
 	return ((sector_t)clus - FAT_START_ENT) * sbi->sec_per_clus
 		+ sbi->data_start;
 }
 
-static inline void fat_get_blknr_offset(struct msdos_sb_info *sbi,
+static inline void fat_get_blknr_offset(const struct msdos_sb_info *sbi,
 				loff_t i_pos, sector_t *blknr, int *offset)
 {
 	*blknr = i_pos >> sbi->dir_per_block_bits;
diff --git a/fs/fat/fat_test.c b/fs/fat/fat_test.c
index 4eeed9dca549..9583ce66dca3 100644
--- a/fs/fat/fat_test.c
+++ b/fs/fat/fat_test.c
@@ -22,7 +22,7 @@ static void fat_checksum_test(struct kunit *test)
 
 static void fat_clus_to_blknr_test(struct kunit *test)
 {
-	struct msdos_sb_info sbi = {
+	static const struct msdos_sb_info sbi = {
 		.sec_per_clus = 4,
 		.data_start = 100,
 	};
@@ -34,7 +34,7 @@ static void fat_clus_to_blknr_test(struct kunit *test)
 
 static void fat_get_blknr_offset_test(struct kunit *test)
 {
-	struct msdos_sb_info sbi = {
+	static const struct msdos_sb_info sbi = {
 		.dir_per_block = 16,
 		.dir_per_block_bits = 4,
 	};