diff --git a/libc/platform/bionic/mte_kernel.h b/libc/platform/bionic/mte_kernel.h
index 984d17d..d22d65e 100644
--- a/libc/platform/bionic/mte_kernel.h
+++ b/libc/platform/bionic/mte_kernel.h
@@ -51,4 +51,6 @@
 #define SEGV_MTEAERR 8
 #define SEGV_MTESERR 9
 
+#define PTRACE_PEEKTAG 33
+
 #endif