diff --git a/os_dep/linux/ioctl_cfg80211.c b/os_dep/linux/ioctl_cfg80211.c
index d19eba7..4540822 100644
--- a/os_dep/linux/ioctl_cfg80211.c
+++ b/os_dep/linux/ioctl_cfg80211.c
@@ -342,7 +342,11 @@ static const struct ieee80211_txrx_stypes
 
 static u64 rtw_get_systime_us(void)
 {
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39))
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4, 20, 0))
+	struct timespec64 ts;
+	ktime_get_boottime_ts64(&ts);
+	return ((u64)ts.tv_sec * 1000000) + ts.tv_nsec / 1000;
+#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39))
 	struct timespec ts;
 	get_monotonic_boottime(&ts);
 	return ((u64)ts.tv_sec * 1000000) + ts.tv_nsec / 1000;