diff --git a/src/eventid.cpp b/src/eventid.cpp
index dd74165b..54ce4026 100644
--- a/src/eventid.cpp
+++ b/src/eventid.cpp
@@ -1,81 +1,81 @@
 /*
  *  eventid.cpp  -  KAlarm unique event identifier for resources
  *  Program:  kalarm
  *  Copyright © 2012-2020 David Jarvie <djarvie@kde.org>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License along
  *  with this program; if not, write to the Free Software Foundation, Inc.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
 
 #include "eventid.h"
 
 #include "resources/resources.h"
 #include "kalarm_debug.h"
 
 #include <QRegularExpression>
 
 /** Set by event ID prefixed by optional resource ID, in the format "[rid:]eid". */
 EventId::EventId(const QString& resourceEventId)
 {
     const QString resourceIdString = extractIDs(resourceEventId, mEventId);
     if (!resourceIdString.isEmpty())
         mResourceId = getResourceId(resourceIdString);  // convert the resource ID string
 }
 
 bool EventId::operator==(const EventId& other) const
 {
     return mEventId == other.mEventId  &&  mResourceId == other.mResourceId;
 }
 
 ResourceId EventId::resourceDisplayId() const
 {
-    return mResourceId & ~ResourceType::IdFlag;
+    return (mResourceId > 0) ? (mResourceId & ~ResourceType::IdFlag) : mResourceId;
 }
 
 QString EventId::extractIDs(const QString& resourceEventId, QString& eventId)
 {
     QRegularExpression rx(QStringLiteral("^(\\w+):(.*)$"));
     QRegularExpressionMatch rxmatch = rx.match(resourceEventId);
     if (!rxmatch.hasMatch())
     {
         eventId = resourceEventId;   // no resource ID supplied
         return QString();
     }
 
     // A resource ID has been supplied
     eventId = rxmatch.captured(2);
     return rxmatch.captured(1);
 }
 
 ResourceId EventId::getResourceId(const QString& resourceIdString)
 {
     // Check if a resource configuration name has been supplied.
     Resource res = Resources::resourceForConfigName(resourceIdString);
     if (res.isValid())
         return res.id();
 
     // Check if a resource ID number has been supplied.
     bool ok;
     const ResourceId id = resourceIdString.toLongLong(&ok);
     if (ok)
     {
         res = Resources::resource(id);
         if (res.isValid())
             return id;
     }
     return -1;
 }
 
 // vim: et sw=4: