diff --git a/APPL/MLD/mld_show_melding.asp b/APPL/MLD/mld_show_melding.asp
index 2dcec0b5ca..4401cff701 100644
--- a/APPL/MLD/mld_show_melding.asp
+++ b/APPL/MLD/mld_show_melding.asp
@@ -61,7 +61,7 @@ if (mld_melding.locked_user_key == user_key)
     mld.unlock(mld_key);
 
 lcl.set_dialect(mld_melding.srtdisc, "MLD_SRTDISCIPLINE_KEY");
-var subjectMail = L("lcl_mld_complain_subject").format((mld_melding.prefix||"")+mld_key, mld_melding.mld_stdmelding_omschrijving, mld_melding.ins_discipline_omschrijving, mld_melding.mld_onderwerp);
+var subjectMail = L("lcl_mld_complain_subject").format((mld_melding.prefix||"")+mld_key, mld_melding.mld_stdmelding_omschrijving, mld_melding.ins_discipline_omschrijving, mld_melding.mld_onderwerp||"");
 var urlMail = "../shared/queuemail.asp?pcode=MLDMAI&defemail_key=" + mld_melding.melder_key
             + "&key=" + mld_key
             + "&subject=" + Server.URLencode(subjectMail)