diff --git a/test/handler_unittest.cpp b/test/handler_unittest.cpp
index a4f9281..99782fa 100644
--- a/test/handler_unittest.cpp
+++ b/test/handler_unittest.cpp
@@ -1,5 +1,6 @@
 #include "errors.hpp"
 #include "handler.hpp"
+#include "handler_impl.hpp"
 
 #include <fstream>
 #include <nlohmann/json.hpp>