diff --git a/src/mesa/state_tracker/st_cb_texture.c b/src/mesa/state_tracker/st_cb_texture.c
index ed3bbc72584..406f11a50ae 100644
--- a/src/mesa/state_tracker/st_cb_texture.c
+++ b/src/mesa/state_tracker/st_cb_texture.c
@@ -1130,11 +1130,15 @@ copy_image_data_to_texture(struct st_context *st,
       /* Copy potentially with the blitter:
        */
       GLuint src_level;
-      if (stImage->pt != stObj->pt)
+      if (stImage->pt->last_level == 0)
          src_level = 0;
       else
          src_level = stImage->base.Level;
 
+      assert(src_level <= stImage->pt->last_level);
+      assert(u_minify(stImage->pt->width0, src_level) == stImage->base.Width);
+      assert(u_minify(stImage->pt->height0, src_level) == stImage->base.Height);
+
       st_texture_image_copy(st->pipe,
                             stObj->pt, dstLevel,  /* dest texture, level */
                             stImage->pt, src_level, /* src texture, level */