diff --git a/libc/sysv/consts.sh b/libc/sysv/consts.sh
index 6b7df79cd..f0af04e88 100755
--- a/libc/sysv/consts.sh
+++ b/libc/sysv/consts.sh
@@ -269,6 +269,7 @@ syscon	madv	MADV_DOFORK				11			11			127			127			127			127			127			127			# TODO(
 syscon	madv	MADV_DONTDUMP				16			16			127			127			127			127			127			127			# see MAP_CONCEAL in OpenBSD; TODO(jart): what is it?
 syscon	madv	MADV_DONTFORK				10			10			127			127			127			127			127			127			# TODO(jart): what is it?
 syscon	madv	MADV_HWPOISON				100			100			127			127			127			127			127			127			# TODO(jart): what is it?
+syscon	madv	MADV_SOFT_OFFLINE				101			101			127			127			127			127			127			127			# TODO: add support ?
 syscon	madv	MADV_REMOVE				9			9			127			127			127			127			127			127			# TODO(jart): what is it?
 syscon	fadv	POSIX_FADV_NOREUSE			5			5			127			127			5			127			5			127			# wut
 
diff --git a/libc/sysv/consts/MADV_SOFT_OFFLINE.S b/libc/sysv/consts/MADV_SOFT_OFFLINE.S
new file mode 100644
index 000000000..a377bacbc
--- /dev/null
+++ b/libc/sysv/consts/MADV_SOFT_OFFLINE.S
@@ -0,0 +1,2 @@
+#include "libc/sysv/consts/syscon.internal.h"
+.syscon madv,MADV_SOFT_OFFLINE,101,101,127,127,127,127,127,127
diff --git a/libc/sysv/consts/madv.h b/libc/sysv/consts/madv.h
index 85aa5b1e9..189ae1a80 100644
--- a/libc/sysv/consts/madv.h
+++ b/libc/sysv/consts/madv.h
@@ -19,6 +19,7 @@ extern const unsigned MADV_REMOVE;
 extern const unsigned MADV_SEQUENTIAL;
 extern const unsigned MADV_UNMERGEABLE;
 extern const unsigned MADV_WILLNEED;
+extern const unsigned MADV_SOFT_OFFLINE;
 
 #define MADV_NORMAL     0
 #define MADV_RANDOM     1