diff --git a/spa/plugins/audioconvert/audioadapter.c b/spa/plugins/audioconvert/audioadapter.c
index ccc9f48df..b5433bf53 100644
--- a/spa/plugins/audioconvert/audioadapter.c
+++ b/spa/plugins/audioconvert/audioadapter.c
@@ -507,6 +507,7 @@ static int negotiate_buffers(struct impl *this)
 
 	if (this->async)
 		buffers = SPA_MAX(2u, buffers);
+	blocks = SPA_MIN(blocks, 256u);
 
 	spa_log_info(this->log, "%p: buffers:%d, blocks:%d, size:%d, stride:%d align:%d %d:%d",
 			this, buffers, blocks, size, stride, align, follower_alloc, conv_alloc);
diff --git a/spa/plugins/videoconvert/videoadapter.c b/spa/plugins/videoconvert/videoadapter.c
index e324b49de..071c5e7d6 100644
--- a/spa/plugins/videoconvert/videoadapter.c
+++ b/spa/plugins/videoconvert/videoadapter.c
@@ -512,6 +512,7 @@ static int negotiate_buffers(struct impl *this)
 
 	if (this->async)
 		buffers = SPA_MAX(2u, buffers);
+	blocks = SPA_MIN(blocks, 256u);
 
 	spa_log_info(this->log, "%p: buffers:%d, blocks:%d, size:%d, stride:%d align:%d %d:%d",
 			this, buffers, blocks, size, stride, align, follower_alloc, conv_alloc);