Index: main.cpp
===================================================================
--- main.cpp
+++ main.cpp
@@ -104,7 +104,7 @@
 
     // command line options
     parser.addOption(QCommandLineOption(QStringList() << QStringLiteral("fullscreen"),
-                                        i18n("Start KRDC with the provided URL in fullscreen mode (works only with one URL)")));
+                                        i18n("Start KRDC in fullscreen mode")));
     parser.addPositionalArgument(QStringLiteral("url"), i18n("URLs to connect after startup"));
 
     parser.process(app);
@@ -128,6 +128,8 @@
 
             mainwindow->newConnection(url, parser.isSet(QStringLiteral("fullscreen")));
         }
+    } else if (parser.isSet(QStringLiteral("fullscreen"))) {
+        mainwindow->switchFullscreen();
     }
     qCDebug(KRDC) << "########## KRDC ready:" << startupTimer.elapsed() << "ms ##########";
 
Index: mainwindow.h
===================================================================
--- mainwindow.h
+++ mainwindow.h
@@ -65,6 +65,7 @@
 
 public Q_SLOTS:
     void newConnection(const QUrl &newUrl = QUrl(), bool switchFullscreenWhenConnected = false, const QString &tabName = QString());
+    void switchFullscreen();
 
 protected:
     void closeEvent(QCloseEvent *event) override;
@@ -83,7 +84,6 @@
     void statusChanged(RemoteView::RemoteStatus status);
     void showRemoteViewToolbar();
     void takeScreenshot();
-    void switchFullscreen();
     void disconnectHost();
     void closeTab(int index);
     void openTabSettings(int index);