diff -Naur qtbase.old/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp qtbase/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
--- qtbase.old/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp	2015-10-13 07:35:27.000000000 +0300
+++ qtbase/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp	2016-01-12 12:31:11.611299079 +0300
@@ -644,7 +644,10 @@
         oldSurface = oldContext->surface();
 
     QScopedPointer<QSurface> surface;
-    const char *glxvendor = glXGetClientString(glXGetCurrentDisplay(), GLX_VENDOR);
+    Display *display = glXGetCurrentDisplay();
+    const char *glxvendor = 0;
+    if (display)
+        glxvendor = glXGetClientString(display, GLX_VENDOR);
     if (glxvendor && !strcmp(glxvendor, "ATI")) {
         QWindow *window = new QWindow;
         window->resize(64, 64);
@@ -661,7 +664,7 @@
     context.create();
     context.makeCurrent(surface.data());
 
-    m_supportsThreading = true;
+    m_supportsThreading = (glxvendor != 0);
 
     if (const char *renderer = (const char *) glGetString(GL_RENDERER)) {
         for (int i = 0; qglx_threadedgl_blacklist_renderer[i]; ++i) {
diff -Naur qtbase.old/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp qtbase/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
--- qtbase.old/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp	2016-01-12 12:27:34.286354000 +0300
+++ qtbase/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp	2016-01-12 12:18:47.176232504 +0300
@@ -195,7 +195,10 @@
     static bool glxPbufferUsable = true;
     if (!vendorChecked) {
         vendorChecked = true;
-        const char *glxvendor = glXGetClientString(glXGetCurrentDisplay(), GLX_VENDOR);
+        Display *display = glXGetCurrentDisplay();
+        const char *glxvendor = 0;
+        if (display)
+            glxvendor = glXGetClientString(display, GLX_VENDOR);
         if (glxvendor && !strcmp(glxvendor, "ATI"))
             glxPbufferUsable = false;
     }