diff --git a/lib/inc/drogon/RateLimiter.h b/lib/inc/drogon/RateLimiter.h
index 3b8706b..dece795 100644
--- a/lib/inc/drogon/RateLimiter.h
+++ b/lib/inc/drogon/RateLimiter.h
@@ -3,6 +3,7 @@
#include <memory>
#include <chrono>
#include <mutex>
+#include <string>
namespace drogon
{