diff --git a/src/mesa/tnl/t_context.c b/src/mesa/tnl/t_context.c
index b5c0b3e..d19d898 100644
--- a/src/mesa/tnl/t_context.c
+++ b/src/mesa/tnl/t_context.c
@@ -189,7 +189,7 @@ _tnl_InvalidateState( struct gl_context *ctx, GLuint new_state )
       }
    }
 
-   if (new_state & (_NEW_VIEWPORT | _NEW_BUFFERS)) {
+   if (ctx->DrawBuffer && (new_state & (_NEW_VIEWPORT | _NEW_BUFFERS))) {
       float scale[3], translate[3];
       _mesa_get_viewport_xform(ctx, 0, scale, translate);
       _math_matrix_viewport(&tnl->_WindowMap, scale, translate,