diff --git a/src/mesa/drivers/dri/unichrome/via_context.c b/src/mesa/drivers/dri/unichrome/via_context.c
index 7c73877..b608a76 100644
--- a/src/mesa/drivers/dri/unichrome/via_context.c
+++ b/src/mesa/drivers/dri/unichrome/via_context.c
@@ -737,7 +737,7 @@ void viaXMesaWindowMoved(struct via_context *vmesa)
    struct via_renderbuffer * read_buffer;
    GLuint bytePerPixel = vmesa->viaScreen->bitsPerPixel >> 3;
 
-   if (!drawable)
+   if (!drawable || !vmesa->glCtx->DrawBuffer)
       return;
 
    draw_buffer =  (struct via_renderbuffer *) drawable->driverPrivate;