diff --git a/Makefile b/Makefile
index 453964d..4b0431d 100755
--- a/Makefile
+++ b/Makefile
@@ -26,6 +26,8 @@ ifeq ($(GCC_VER_49),1)
 EXTRA_CFLAGS += -Wno-date-time -Wno-error=date-time # Fix compile error && warning on gcc 4.9 and later
 endif
 
+EXTRA_CFLAGS += -Wno-vla
+
 EXTRA_CFLAGS += -I$(src)/include
 
 EXTRA_LDFLAGS += --strip-debug
diff --git a/os_dep/linux/ioctl_cfg80211.c b/os_dep/linux/ioctl_cfg80211.c
index 1ede452..cfb2ed0 100644
--- a/os_dep/linux/ioctl_cfg80211.c
+++ b/os_dep/linux/ioctl_cfg80211.c
@@ -692,7 +692,11 @@ static u64 rtw_get_systime_us(void)
 	return do_div(ts, 1000);
 #elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39))
 	struct timespec ts;
+#if (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;
 #else
 	struct timeval tv;