diff --git a/Control/StoreGate/StoreGate/ReadCondHandle.h b/Control/StoreGate/StoreGate/ReadCondHandle.h
index 6e2a245deba11e8bff3084f9faae0e5e98a57e67..ae81e5c1bdbf9b4d521b1c66da2d5c990206a250 100644
--- a/Control/StoreGate/StoreGate/ReadCondHandle.h
+++ b/Control/StoreGate/StoreGate/ReadCondHandle.h
@@ -92,6 +92,8 @@ namespace SG {
     if (conditionsRun != EventIDBase::UNDEFNUM) {
       m_eid.set_run_number (conditionsRun);
     }
+    // Event number not used in IOV comparisons, only run+lbn.
+    m_eid.set_event_number (EventIDBase::UNDEFEVT);
 
     if (! m_hkey.isInit()) {
       MsgStream msg(Athena::getMessageSvc(), "ReadCondHandle");