diff --git a/bufferevent_filter.c b/bufferevent_filter.c
index e8e1f6f5..fd0f236f 100644
--- a/bufferevent_filter.c
+++ b/bufferevent_filter.c
@@ -155,7 +155,7 @@ be_null_filter(struct evbuffer *src, struct evbuffer *dst, ssize_t lim,
 	       enum bufferevent_flush_mode state, void *ctx)
 {
 	(void)state;
-	if (evbuffer_remove_buffer(src, src, lim) == 0)
+	if (evbuffer_remove_buffer(src, dst, lim) == 0)
 		return BEV_OK;
 	else
 		return BEV_ERROR;