diff --git a/lib/mqtt.c b/lib/mqtt.c
index 5f5c91a49a..fc3389e7f5 100644
--- a/lib/mqtt.c
+++ b/lib/mqtt.c
@@ -562,7 +562,7 @@ static CURLcode mqtt_publish(struct Curl_easy *data)
 
   remaininglength = payloadlen + 2 + topiclen;
   encodelen = mqtt_encode_len(encodedbytes, remaininglength);
-  if(MAX_MQTT_MESSAGE_SIZE - remaininglength - 1 < encodelen) {
+  if(remaininglength > (MAX_MQTT_MESSAGE_SIZE - encodelen - 1)) {
     result = CURLE_TOO_LARGE;
     goto fail;
   }