diff --git a/include/cppkafka/utils/buffered_producer.h b/include/cppkafka/utils/buffered_producer.h
index 0ee3f93d..8f3a9b2c 100644
--- a/include/cppkafka/utils/buffered_producer.h
+++ b/include/cppkafka/utils/buffered_producer.h
@@ -708,6 +708,7 @@ bool BufferedProducer<BufferType, Allocator>::flush(std::chrono::milliseconds ti
         };
         re_enqueuer(retry_flush_queue, retry_messages_, retry_mutex_);
         re_enqueuer(flush_queue, messages_, mutex_);
+        return true;
     }
     else {
         async_flush();
@@ -811,7 +812,7 @@ void BufferedProducer<BufferType, Allocator>::do_add_message(BuilderType&& build
 
     // Flush the queues only if a regular message is added. Retry messages may be added
     // from rdkafka callbacks, and flush/async_flush is a user-level call
-    if (queue_kind == QueueKind::Regular && flush_action == FlushAction::DoFlush && (max_buffer_size_ >= 0) && (max_buffer_size_ <= get_buffer_size())) {
+    if (queue_kind == QueueKind::Regular && flush_action == FlushAction::DoFlush && (max_buffer_size_ >= 0) && (max_buffer_size_ <= (ssize_t)get_buffer_size())) {
         if (flush_method_ == FlushMethod::Sync) {
             flush();
         }