diff --git a/src/library/user_recursors.cpp b/src/library/user_recursors.cpp
index 559acb028..4a85ea4ec 100644
--- a/src/library/user_recursors.cpp
+++ b/src/library/user_recursors.cpp
@@ -4,6 +4,8 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#include <algorithm>
+#include <string>
 #include "util/sstream.h"
 #include "kernel/inductive/inductive.h"
 #include "library/scoped_ext.h"