diff --git a/src/sna/sna_dri.c b/src/sna/sna_dri.c
index d647c02c..1daf1c47 100644
--- a/src/sna/sna_dri.c
+++ b/src/sna/sna_dri.c
@@ -397,6 +397,7 @@ static void damage(PixmapPtr pixmap, RegionPtr region)
 	struct sna_pixmap *priv;
 
 	priv = sna_pixmap(pixmap);
+	assert(priv != NULL);
 	if (DAMAGE_IS_ALL(priv->gpu_damage))
 		return;