diff --git a/libc/kernel/uapi/linux/magic.h b/libc/kernel/uapi/linux/magic.h
index 19ef392..7c7c6c3 100644
--- a/libc/kernel/uapi/linux/magic.h
+++ b/libc/kernel/uapi/linux/magic.h
@@ -93,4 +93,6 @@
 /* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */
 #define MTD_INODE_FS_MAGIC 0x11307854
 #define ANON_INODE_FS_MAGIC 0x09041934
+#define BTRFS_TEST_MAGIC 0x73727279
 #endif
+/* WARNING: DO NOT EDIT, AUTO-GENERATED CODE - SEE TOP FOR INSTRUCTIONS */