diff --git a/libc/kernel/uapi/asm-arm64/asm/hwcap.h b/libc/kernel/uapi/asm-arm64/asm/hwcap.h
index 8a70a52..d4d4324 100644
--- a/libc/kernel/uapi/asm-arm64/asm/hwcap.h
+++ b/libc/kernel/uapi/asm-arm64/asm/hwcap.h
@@ -69,4 +69,5 @@
 #define HWCAP2_RNG (1 << 16)
 #define HWCAP2_BTI (1 << 17)
 #define HWCAP2_MTE (1 << 18)
+#define HWCAP2_ECV (1 << 19)
 #endif