diff --git a/3rdparty/qtsingleapplication/qtsingleapplication.cpp b/3rdparty/qtsingleapplication/qtsingleapplication.cpp
index f9a92e04d..d26128ebc 100644
--- a/3rdparty/qtsingleapplication/qtsingleapplication.cpp
+++ b/3rdparty/qtsingleapplication/qtsingleapplication.cpp
@@ -45,10 +45,6 @@
 #include <QWidget>
 #include <QString>
 
-#ifdef HAVE_X11_ // FIXME
-#  include <X11/Xlib.h>
-#endif
-
 #include "qtlocalpeer.h"
 
 /*!
@@ -178,47 +174,6 @@ QtSingleApplication::QtSingleApplication(const QString &appId, int &argc, char *
 }
 
 
-#if defined(HAVE_X11_) // FIXME
-/*!
-  Special constructor for X11, ref. the documentation of
-  QApplication's corresponding constructor. The application identifier
-  will be QCoreApplication::applicationFilePath(). \a dpy, \a visual,
-  and \a cmap are passed on to the QApplication constructor.
-*/
-QtSingleApplication::QtSingleApplication(Display *dpy, Qt::HANDLE visual, Qt::HANDLE cmap)
-    : QApplication(dpy, visual, cmap)
-{
-    sysInit();
-}
-
-/*!
-  Special constructor for X11, ref. the documentation of
-  QApplication's corresponding constructor. The application identifier
-  will be QCoreApplication::applicationFilePath(). \a dpy, \a argc, \a
-  argv, \a visual, and \a cmap are passed on to the QApplication
-  constructor.
-*/
-QtSingleApplication::QtSingleApplication(Display *dpy, int &argc, char **argv, Qt::HANDLE visual, Qt::HANDLE cmap)
-    : QApplication(dpy, argc, argv, visual, cmap)
-{
-    sysInit();
-}
-
-/*!
-  Special constructor for X11, ref. the documentation of
-  QApplication's corresponding constructor. The application identifier
-  will be \a appId. \a dpy, \a argc, \a
-  argv, \a visual, and \a cmap are passed on to the QApplication
-  constructor.
-*/
-QtSingleApplication::QtSingleApplication(Display *dpy, const QString &appId, int argc, char **argv, Qt::HANDLE visual, Qt::HANDLE cmap)
-    : QApplication(dpy, argc, argv, visual, cmap)
-{
-    sysInit(appId);
-}
-#endif
-
-
 /*!
     Returns true if another instance of this application is running;
     otherwise false.
diff --git a/3rdparty/qtsingleapplication/qtsingleapplication.h b/3rdparty/qtsingleapplication/qtsingleapplication.h
index 96bc6a5e4..bd620ed28 100644
--- a/3rdparty/qtsingleapplication/qtsingleapplication.h
+++ b/3rdparty/qtsingleapplication/qtsingleapplication.h
@@ -48,10 +48,6 @@
 #include <QApplication>
 #include <QString>
 
-#if defined(HAVE_X11_) // FIXME
-#  include <X11/Xlib.h>
-#endif
-
 class QtLocalPeer;
 
 #if defined(Q_OS_WIN) || defined(Q_OS_WIN32)
@@ -77,11 +73,6 @@ class QT_QTSINGLEAPPLICATION_EXPORT QtSingleApplication : public QApplication
 public:
     QtSingleApplication(int &argc, char **argv, bool GUIenabled = true);
     QtSingleApplication(const QString &id, int &argc, char **argv);
-#if defined(HAVE_X11_) // FIXME
-    QtSingleApplication(Display *dpy, Qt::HANDLE visual = 0, Qt::HANDLE colormap = 0);
-    QtSingleApplication(Display *dpy, int &argc, char **argv, Qt::HANDLE visual = 0, Qt::HANDLE cmap= 0);
-    QtSingleApplication(Display *dpy, const QString &appId, int argc, char **argv, Qt::HANDLE visual = 0, Qt::HANDLE colormap = 0);
-#endif
 
     bool isRunning();
     QString id() const;