diff --git a/libc/kernel/uapi/linux/fs.h b/libc/kernel/uapi/linux/fs.h
index 9288653..f1a8eac 100644
--- a/libc/kernel/uapi/linux/fs.h
+++ b/libc/kernel/uapi/linux/fs.h
@@ -192,6 +192,7 @@
 #define PAGE_IS_SWAPPED (1 << 4)
 #define PAGE_IS_PFNZERO (1 << 5)
 #define PAGE_IS_HUGE (1 << 6)
+#define PAGE_IS_SOFT_DIRTY (1 << 7)
 struct page_region {
   __u64 start;
   __u64 end;