diff --git a/spice.proto b/spice.proto
index 0773f0a..67acb67 100644
--- a/spice.proto
+++ b/spice.proto
@@ -412,7 +412,7 @@ struct Clip {
     clip_type type;
     switch (type) {
     case RECTS:
-        ClipRects *rects @outvar(cliprects) @c_ptr;
+        ClipRects *rects @outvar(cliprects) @c_ptr @marshall @nonnull;
     } u @anon;
 };