diff --git a/panda/src/glxdisplay/glxGraphicsStateGuardian.cxx b/panda/src/glxdisplay/glxGraphicsStateGuardian.cxx
index c94aa9a2dd..bd38035071 100644
--- a/panda/src/glxdisplay/glxGraphicsStateGuardian.cxx
+++ b/panda/src/glxdisplay/glxGraphicsStateGuardian.cxx
@@ -56,6 +56,7 @@ glxGraphicsStateGuardian(const FrameBufferProperties &properties,
   
   _libgl_handle = NULL;
   _checked_get_proc_address = false;
+  _glxGetProcAddress = NULL;
 }
 
 ////////////////////////////////////////////////////////////////////