diff --git a/include/vde/sdf/sdf_tree.h b/include/vde/sdf/sdf_tree.h
index 0c7d7d0..b2f9b3a 100644
--- a/include/vde/sdf/sdf_tree.h
+++ b/include/vde/sdf/sdf_tree.h
@@ -118,7 +118,7 @@ public:
         for (auto& c : children) c->visit(std::forward<Fn>(fn));
     }
 
-private:
+public:
     explicit SdfNode(SdfOp o) : op(o) {}
 };