diff --git a/include/osgViewer/api/X11/PixelBufferX11 b/include/osgViewer/api/X11/PixelBufferX11
index 9e815f8a3..19806c148 100644
--- a/include/osgViewer/api/X11/PixelBufferX11
+++ b/include/osgViewer/api/X11/PixelBufferX11
@@ -85,6 +85,7 @@ class OSGVIEWER_EXPORT PixelBufferX11 : public osg::GraphicsContext, public osgV
         bool            _useGLX1_3;
         bool            _useSGIX;
 
+#ifdef GLX_SGIX_pbuffer
         typedef Pbuffer ( *GLXCreateGLXPbufferSGIX_FuncPtr) (Display *dpy, GLXFBConfig config, unsigned int, unsigned height, int* attrib_list);
         typedef void ( *GLXDestroyGLXPbufferSGIX_FuncPtr) (Display *dpy, Pbuffer pbuf);
         typedef int ( *GLXQueryGLXPbufferSGIX_FuncCPtr) (Display *dpy, Pbuffer pbuf, int attribute, unsigned int *value);
@@ -94,6 +95,7 @@ class OSGVIEWER_EXPORT PixelBufferX11 : public osg::GraphicsContext, public osgV
         GLXDestroyGLXPbufferSGIX_FuncPtr _glXDestroyGLXPbufferSGIX;
         GLXQueryGLXPbufferSGIX_FuncCPtr _glXQueryGLXPbufferSGIX;
         GLXGetFBConfigFromVisualSGIX_FuncPtr _glXGetFBConfigFromVisualSGIX;
+#endif
 };
 
 }
diff --git a/src/osgViewer/PixelBufferX11.cpp b/src/osgViewer/PixelBufferX11.cpp
index 8661af14e..5e7f9b280 100644
--- a/src/osgViewer/PixelBufferX11.cpp
+++ b/src/osgViewer/PixelBufferX11.cpp
@@ -33,12 +33,14 @@ PixelBufferX11::PixelBufferX11(osg::GraphicsContext::Traits* traits)
     _initialized(false),
     _realized(false),
     _useGLX1_3(false),
-    _useSGIX(false),
-    _glXCreateGLXPbufferSGIX(NULL),
+    _useSGIX(false)
+#ifdef GLX_SGIX_pbuffer
+    ,_glXCreateGLXPbufferSGIX(NULL),
     _glXDestroyGLXPbufferSGIX(NULL),
     _glXQueryGLXPbufferSGIX(NULL),
     _glXGetFBConfigFromVisualSGIX(NULL)
-{
+#endif
+    {
     _traits = traits;
 
     init();
@@ -179,7 +181,7 @@ void PixelBufferX11::init()
         haveGLX1_3 = true;
     }
 
-#if defined(GLX_VERSION_1_1)
+#if defined(GLX_VERSION_1_1) && defined(GLX_SGIX_pbuffer)
     // We need at least GLX 1.1 for glXQueryExtensionsString
     if (!haveGLX1_3 && 1 <= minor)
     {