diff --git a/os_dep/linux/ioctl_cfg80211.c b/os_dep/linux/ioctl_cfg80211.c
index 3acf030..01fab29 100644
--- a/os_dep/linux/ioctl_cfg80211.c
+++ b/os_dep/linux/ioctl_cfg80211.c
@@ -686,18 +686,12 @@ static int rtw_cfg80211_sync_iftype(_adapter *adapter)
 
 static u64 rtw_get_systime_us(void)
 {
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0))
-	struct timespec64 ts;
-#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39))
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39) && LINUX_VERSION_CODE < KERNEL_VERSION(4, 20, 0))
 	struct timespec ts;
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0))
-	getboottime64(&ts);
-#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(4, 20, 0))
-	getboottime(&ts);
-#else
 	get_monotonic_boottime(&ts);
-#endif
 	return ((u64)ts.tv_sec * 1000000) + ts.tv_nsec / 1000;
+#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(4, 20, 0))
+	return ktime_to_us(ktime_get_boottime());
 #else
 	struct timeval tv;
 	do_gettimeofday(&tv);