diff --git a/src/QtLocationPlugin/QMLControl/QGCMapEngineManager.cc b/src/QtLocationPlugin/QMLControl/QGCMapEngineManager.cc
index 88f31a4..2882eac 100644
--- a/src/QtLocationPlugin/QMLControl/QGCMapEngineManager.cc
+++ b/src/QtLocationPlugin/QMLControl/QGCMapEngineManager.cc
@@ -96,14 +96,14 @@ QGCMapEngineManager::updateForCurrentView(double lon0, double lat0, double lon1,
 
 //-----------------------------------------------------------------------------
 QString
-QGCMapEngineManager::tileCountStr()
+QGCMapEngineManager::tileCountStr() const
 {
     return QGCMapEngine::numberToString(_imageSet.tileCount + _elevationSet.tileCount);
 }
 
 //-----------------------------------------------------------------------------
 QString
-QGCMapEngineManager::tileSizeStr()
+QGCMapEngineManager::tileSizeStr() const
 {
     return QGCMapEngine::bigSizeToString(_imageSet.tileSize + _elevationSet.tileSize);
 }
diff --git a/src/QtLocationPlugin/QMLControl/QGCMapEngineManager.h b/src/QtLocationPlugin/QMLControl/QGCMapEngineManager.h
index 70c9bc6..b7defc1 100644
--- a/src/QtLocationPlugin/QMLControl/QGCMapEngineManager.h
+++ b/src/QtLocationPlugin/QMLControl/QGCMapEngineManager.h
@@ -73,10 +73,10 @@ public:
     Q_INVOKABLE bool                importSets              (QString path = QString());
     Q_INVOKABLE void                resetAction             ();
 
-    quint64                         tileCount               () { return _imageSet.tileCount + _elevationSet.tileCount; }
-    QString                         tileCountStr            ();
-    quint64                         tileSize                () { return _imageSet.tileSize + _elevationSet.tileSize; }
-    QString                         tileSizeStr             ();
+    quint64                         tileCount               () const{ return _imageSet.tileCount + _elevationSet.tileCount; }
+    QString                         tileCountStr            () const;
+    quint64                         tileSize                () const{ return _imageSet.tileSize + _elevationSet.tileSize; }
+    QString                         tileSizeStr             () const;
     QStringList                     mapList                 ();
     QStringList                     mapProviderList         ();
     Q_INVOKABLE QStringList         mapTypeList             (QString provider);
@@ -84,13 +84,13 @@ public:
     quint32                         maxMemCache             ();
     quint32                         maxDiskCache            ();
     QString                         errorMessage            () { return _errorMessage; }
-    bool                            fetchElevation          () { return _fetchElevation; }
-    quint64                         freeDiskSpace           () { return _freeDiskSpace; }
-    quint64                         diskSpace               () { return _diskSpace; }
+    bool                            fetchElevation          () const{ return _fetchElevation; }
+    quint64                         freeDiskSpace           () const{ return _freeDiskSpace; }
+    quint64                         diskSpace               () const{ return _diskSpace; }
     int                             selectedCount           ();
-    int                             actionProgress          () { return _actionProgress; }
+    int                             actionProgress          () const{ return _actionProgress; }
     ImportAction                    importAction            () { return _importAction; }
-    bool                            importReplace           () { return _importReplace; }
+    bool                            importReplace           () const{ return _importReplace; }
 
     void                            setMaxMemCache          (quint32 size);
     void                            setMaxDiskCache         (quint32 size);