diff --git a/libc/kernel/uapi/linux/gpio.h b/libc/kernel/uapi/linux/gpio.h
index a3836ff..7e010d9 100644
--- a/libc/kernel/uapi/linux/gpio.h
+++ b/libc/kernel/uapi/linux/gpio.h
@@ -41,6 +41,7 @@
   GPIO_V2_LINE_FLAG_BIAS_PULL_UP = _BITULL(8),
   GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN = _BITULL(9),
   GPIO_V2_LINE_FLAG_BIAS_DISABLED = _BITULL(10),
+  GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME = _BITULL(11),
 };
 struct gpio_v2_line_values {
   __aligned_u64 bits;