--- glxcmds.c.orig	2004-08-04 20:18:42.210502613 -0400
+++ glxcmds.c	2004-08-04 19:50:59.000000000 -0400
@@ -657,7 +657,8 @@
 
     if (prevglxc) {
 	if (prevglxc->drawPixmap) {
-	    if (prevglxc->drawPixmap != prevglxc->readPixmap) {
+	    if (prevglxc->readPixmap && 
+	        prevglxc->drawPixmap != prevglxc->readPixmap) {
 		/*
 		** The previous drawable was a glx pixmap, release it.
 		*/