diff --git a/include/boost/variant2/variant.hpp b/include/boost/variant2/variant.hpp
index e99382c..069823a 100644
--- a/include/boost/variant2/variant.hpp
+++ b/include/boost/variant2/variant.hpp
@@ -25,6 +25,7 @@
 #include <cassert>
 #include <initializer_list>
 #include <utility>
+#include <functional> // std::hash
 
 //