diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index d44bfc392491..23146ff2a25b 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -87,6 +87,9 @@ bool vkms_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
 
 	*vblank_time = output->vblank_hrtimer.node.expires;
 
+	if (!in_vblank_irq)
+		*vblank_time -= output->period_ns;
+
 	return true;
 }