diff --git a/CHANGELOG.md b/CHANGELOG.md
index d90671c6..9d51891d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -84,6 +84,7 @@
 - Change arduinoWebSockets URL param to path ([#278](https://github.com/matth-x/MicroOcpp/issues/278))
 - Avoid creating conf when operation fails ([#290](https://github.com/matth-x/MicroOcpp/pull/290))
 - Fix whitespaces in MeterValues ([#301](https://github.com/matth-x/MicroOcpp/pull/301))
+- Make SmartChargingProfile txId field optional ([#348](https://github.com/matth-x/MicroOcpp/pull/348))
 
 ## [1.0.3] - 2024-04-06
 
diff --git a/src/MicroOcpp/Operations/SetChargingProfile.cpp b/src/MicroOcpp/Operations/SetChargingProfile.cpp
index 20cf5ca8..1e991bbd 100644
--- a/src/MicroOcpp/Operations/SetChargingProfile.cpp
+++ b/src/MicroOcpp/Operations/SetChargingProfile.cpp
@@ -65,7 +65,7 @@ void SetChargingProfile::processReq(JsonObject payload) {
             return;
         }
 
-        if (chargingProfile->getTransactionId() < 0 ||
+        if (chargingProfile->getTransactionId() >= 0 &&
                 chargingProfile->getTransactionId() != transaction->getTransactionId()) {
             //transactionId undefined / mismatch
             accepted = false;