diff --git a/src/sna/sna_dri.c b/src/sna/sna_dri.c
index 880e9f6a..f7fd2931 100644
--- a/src/sna/sna_dri.c
+++ b/src/sna/sna_dri.c
@@ -456,6 +456,9 @@ static void set_bo(PixmapPtr pixmap, struct kgem_bo *bo)
 	struct sna_pixmap *priv = sna_pixmap(pixmap);
 	RegionRec region;
 
+	assert(pixmap->drawable.width * pixmap->drawable.bitsPerPixel <= 8*bo->pitch);
+	assert(pixmap->drawable.height * bo->pitch <= kgem_bo_size(bo));
+
 	/* Post damage on the new front buffer so that listeners, such
 	 * as DisplayLink know take a copy and shove it over the USB,
 	 * also for software cursors and the like.