diff --git a/lib/pubsubclient/src/PubSubClient.cpp b/lib/pubsubclient/src/PubSubClient.cpp
index 4f8b9b3be..61fa130b5 100644
--- a/lib/pubsubclient/src/PubSubClient.cpp
+++ b/lib/pubsubclient/src/PubSubClient.cpp
@@ -445,7 +445,9 @@ boolean PubSubClient::publish_P(const char* topic, const uint8_t* payload, unsig
 
     lastOutActivity = millis();
 
-    return rc == tlen + 4 + plength;
+    // Header (1 byte) + llen + identifier (2 bytes)  + topic len + payload len
+    const int expectedLength = 1 + llen + 2 + tlen + plength;
+    return (rc == expectedLength);
 }
 
 boolean PubSubClient::beginPublish(const char* topic, unsigned int plength, boolean retained) {