--- src/mesa/main/context.c.orig	2007-08-01 22:50:00.000000000 +0100
+++ src/mesa/main/context.c	2007-10-31 17:14:10.000000000 +0000
@@ -1431,6 +1431,12 @@
 _mesa_make_current( GLcontext *newCtx, GLframebuffer *drawBuffer,
                     GLframebuffer *readBuffer )
 {
+
+   if (newCtx) {
+     assert(drawBuffer);
+     assert(readBuffer);
+   }
+
    GET_CURRENT_CONTEXT(oldCtx);
 
    if (MESA_VERBOSE & VERBOSE_API)