diff --git a/libs/core/synchronization/include/hpx/synchronization/range_lock.hpp b/libs/core/synchronization/include/hpx/synchronization/range_lock.hpp
index 34b0af7c4d4..555460efb2c 100644
--- a/libs/core/synchronization/include/hpx/synchronization/range_lock.hpp
+++ b/libs/core/synchronization/include/hpx/synchronization/range_lock.hpp
@@ -1,10 +1,11 @@
 #pragma once
 
-#include <mutex>
-
 #include <hpx/synchronization/detail/range_lock_impl.hpp>
 #include <hpx/synchronization/spinlock.hpp>
 
+#include <functional>
+#include <mutex>
+
 namespace hpx::synchronization {
     using range_lock =
         hpx::synchronization::detail::RangeLock<hpx::spinlock, std::lock_guard>;