2 files changed, 13 insertions, 2 deletions
diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
index eea7e6a2d4..ff624d9755 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
@@ -658,7 +658,13 @@ void QGLXContext::queryDummyContext()
         oldSurface = oldContext->surface();
 
     QScopedPointer<QSurface> surface;
-    const char *glxvendor = glXGetClientString(glXGetCurrentDisplay(), GLX_VENDOR);
+    Display *display = glXGetCurrentDisplay();
+    if (!display) {
+        // FIXME: Since Qt 5.6 we don't need to check whether primary screen is NULL
+        if (QScreen *screen = QGuiApplication::primaryScreen())
+            display = DISPLAY_FROM_XCB(static_cast<QXcbScreen *>(screen->handle()));
+    }
+    const char *glxvendor = glXGetClientString(display, GLX_VENDOR);
     if (glxvendor && !strcmp(glxvendor, "ATI")) {
         QWindow *window = new QWindow;
         window->resize(64, 64);
diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
index 38e996fdb4..3e963ccaa8 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
@@ -201,7 +201,12 @@ QPlatformOffscreenSurface *QXcbGlxIntegration::createPlatformOffscreenSurface(QO
     static bool glxPbufferUsable = true;
     if (!vendorChecked) {
         vendorChecked = true;
-        const char *glxvendor = glXGetClientString(glXGetCurrentDisplay(), GLX_VENDOR);
+        Display *display = glXGetCurrentDisplay();
+#ifdef XCB_USE_XLIB
+        if (!display)
+            display = static_cast<Display *>(m_connection->xlib_display());
+#endif
+        const char *glxvendor = glXGetClientString(display, GLX_VENDOR);
         if (glxvendor && !strcmp(glxvendor, "ATI"))
             glxPbufferUsable = false;
     }