diff --git a/src/sna/sna_accel.c b/src/sna/sna_accel.c
index ba8c93d5..9731a0a3 100644
--- a/src/sna/sna_accel.c
+++ b/src/sna/sna_accel.c
@@ -2561,6 +2561,7 @@ use_gpu_bo:
 	return priv->gpu_bo;
 
 use_cpu_bo:
+	assert(!priv->clear);
 	if (priv->cpu_bo == NULL)
 		return NULL;