diff --git a/src/tests/shared/options.c b/src/tests/shared/options.c
index e5f4cf30ca..11e95c2952 100644
--- a/src/tests/shared/options.c
+++ b/src/tests/shared/options.c
@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include "api/lean.h"