diff --git a/immer/detail/hamts/champ.hpp b/immer/detail/hamts/champ.hpp
index 77cf7e47..30075d6b 100644
--- a/immer/detail/hamts/champ.hpp
+++ b/immer/detail/hamts/champ.hpp
@@ -34,10 +34,11 @@ struct champ
     node_t* root;
     size_t size;
 
-    static node_t* empty()
+    static node_t*& empty()
     {
-        static const auto node = node_t::make_inner_n(0);
-        return node->inc();
+        static auto node = node_t::make_inner_n(0);
+        node->inc();
+        return node;
     }
 
     champ(node_t* r, size_t sz = 0)
diff --git a/immer/detail/rbts/rrbtree.hpp b/immer/detail/rbts/rrbtree.hpp
index 9288670b..4e67710a 100644
--- a/immer/detail/rbts/rrbtree.hpp
+++ b/immer/detail/rbts/rrbtree.hpp
@@ -47,16 +47,18 @@ struct rrbtree
                ipow((size_t{1} << B) - 2, (S - BL) / B);
     }
 
-    static node_t* empty_root()
+    static node_t*& empty_root()
     {
-        static const auto empty_ = node_t::make_inner_n(0u);
-        return empty_->inc();
+        static auto empty_ = node_t::make_inner_n(0u);
+        empty_->inc();
+        return empty_;
     }
 
-    static node_t* empty_tail()
+    static node_t*& empty_tail()
     {
-        static const auto empty_ = node_t::make_leaf_n(0u);
-        return empty_->inc();
+        static auto empty_ = node_t::make_leaf_n(0u);
+        empty_->inc();
+        return empty_;
     }
 
     template <typename U>