diff --git a/DataFormats/simulation/include/SimulationDataFormat/MCEventHeader.h b/DataFormats/simulation/include/SimulationDataFormat/MCEventHeader.h
index 2a0338828ac17..863220e5f10bb 100644
--- a/DataFormats/simulation/include/SimulationDataFormat/MCEventHeader.h
+++ b/DataFormats/simulation/include/SimulationDataFormat/MCEventHeader.h
@@ -94,7 +94,7 @@ class MCEventHeader : public FairMCEventHeader
   MCEventStats mEventStats{};
   o2::utils::RootSerializableKeyValueStore mEventInfo;
 
-  ClassDefOverride(MCEventHeader, 2);
+  ClassDefOverride(MCEventHeader, 3);
 
 }; /** class MCEventHeader **/