diff --git a/src/kernel/replace_visitor.h b/src/kernel/replace_visitor.h
index a0dd57608c..bfe389e2ea 100644
--- a/src/kernel/replace_visitor.h
+++ b/src/kernel/replace_visitor.h
@@ -16,7 +16,7 @@ namespace lean {
 */
 class replace_visitor {
 protected:
-    typedef expr_map<expr> cache;
+    typedef expr_bi_struct_map<expr> cache;
     cache   m_cache;
     expr save_result(expr const & e, expr && r, bool shared);
     virtual expr visit_sort(expr const &);