diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 59c71fa8c553..2a616aa3f686 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -311,6 +311,7 @@ struct fscrypt_key {
 #define FS_NOCOW_FL			0x00800000 /* Do not cow file */
 #define FS_INLINE_DATA_FL		0x10000000 /* Reserved for ext4 */
 #define FS_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
+#define FS_CASEFOLD_FL			0x40000000 /* Folder is case insensitive */
 #define FS_RESERVED_FL			0x80000000 /* reserved for ext2 lib */
 
 #define FS_FL_USER_VISIBLE		0x0003DFFF /* User visible flags */
diff --git a/tools/include/uapi/linux/fs.h b/tools/include/uapi/linux/fs.h
index 59c71fa8c553..2a616aa3f686 100644
--- a/tools/include/uapi/linux/fs.h
+++ b/tools/include/uapi/linux/fs.h
@@ -311,6 +311,7 @@ struct fscrypt_key {
 #define FS_NOCOW_FL			0x00800000 /* Do not cow file */
 #define FS_INLINE_DATA_FL		0x10000000 /* Reserved for ext4 */
 #define FS_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
+#define FS_CASEFOLD_FL			0x40000000 /* Folder is case insensitive */
 #define FS_RESERVED_FL			0x80000000 /* reserved for ext2 lib */
 
 #define FS_FL_USER_VISIBLE		0x0003DFFF /* User visible flags */