diff --git a/libc/kernel/uapi/linux/prctl.h b/libc/kernel/uapi/linux/prctl.h
index ba50b14..44a088d 100644
--- a/libc/kernel/uapi/linux/prctl.h
+++ b/libc/kernel/uapi/linux/prctl.h
@@ -137,6 +137,7 @@
 #define PR_GET_SPECULATION_CTRL 52
 #define PR_SET_SPECULATION_CTRL 53
 #define PR_SPEC_STORE_BYPASS 0
+#define PR_SPEC_INDIRECT_BRANCH 1
 #define PR_SPEC_NOT_AFFECTED 0
 #define PR_SPEC_PRCTL (1UL << 0)
 #define PR_SPEC_ENABLE (1UL << 1)