diff --git a/src/library/tactic/location.cpp b/src/library/tactic/location.cpp
index 63f665cb2..70b2abbd5 100644
--- a/src/library/tactic/location.cpp
+++ b/src/library/tactic/location.cpp
@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#include <string>
 #include "kernel/replace_fn.h"
 #include "library/kernel_serializer.h"
 #include "library/tactic/location.h"
diff --git a/src/library/tactic/with_options_tactic.cpp b/src/library/tactic/with_options_tactic.cpp
index 4c4cca0ed..04704eebf 100644
--- a/src/library/tactic/with_options_tactic.cpp
+++ b/src/library/tactic/with_options_tactic.cpp
@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#include <string>
 #include "kernel/type_checker.h"
 #include "library/kernel_serializer.h"
 #include "library/tactic/tactic.h"