diff --git a/RTCP/Cobalt/CoInterface/src/Parset.cc b/RTCP/Cobalt/CoInterface/src/Parset.cc
index 9ad9d831eb946479d6e956618d918ff1ecb680f8..db387776f0a8d5e75c49cc11b56f4fa8f7194b75 100644
--- a/RTCP/Cobalt/CoInterface/src/Parset.cc
+++ b/RTCP/Cobalt/CoInterface/src/Parset.cc
@@ -938,7 +938,7 @@ namespace LOFAR
           const ObservationSettings::AntennaFieldName& afName = settings.rspRaw.antennaFieldNames[i];
           vector<ObservationSettings::AntennaFieldName>::iterator nameIt = std::find(settings.antennaFieldNames.begin(),
                                                                                      settings.antennaFieldNames.end(), afName);
-          ASSERTSTR(nameIt == settings.antennaFieldNames.end(), "RSP raw antenna field name " << afName.fullName() <<
+          ASSERTSTR(nameIt != settings.antennaFieldNames.end(), "RSP raw antenna field name " << afName.fullName() <<
                                                                 " missing in observation antenna field list"); // getOutputTypeAntennaFieldNames() must have avoided this
           vector<ObservationSettings::AntennaField>::iterator afIt = settings.antennaFields.begin() +
                                               std::distance(settings.antennaFieldNames.begin(), nameIt);