diff --git a/src/libraries/turtle/error.hpp b/src/libraries/turtle/error.hpp
index 7c9c4fa..83bbc97 100644
--- a/src/libraries/turtle/error.hpp
+++ b/src/libraries/turtle/error.hpp
@@ -19,6 +19,7 @@
 #else
 #include <iostream>
 #endif
+#include <string>
 
 namespace mock
 {