diff --git a/tests/helper/vector_approx.hpp b/tests/helper/vector_approx.hpp
index c4ddd3b..40d0f0b 100644
--- a/tests/helper/vector_approx.hpp
+++ b/tests/helper/vector_approx.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include <algorithm>
 #include <string>
 #include <vector>