diff --git a/source/mijin/async/signal.hpp b/source/mijin/async/signal.hpp
index 33459c5..72a102d 100644
--- a/source/mijin/async/signal.hpp
+++ b/source/mijin/async/signal.hpp
@@ -4,6 +4,7 @@
 #if !defined(MIJIN_ASYNC_SIGNAL_HPP_INCLUDED)
 #define MIJIN_ASYNC_SIGNAL_HPP_INCLUDED 1
 
+#include <algorithm>
 #include <cstdint>
 #include <functional>
 #include <memory>
diff --git a/source/mijin/util/iterators.hpp b/source/mijin/util/iterators.hpp
index 5907466..3552556 100644
--- a/source/mijin/util/iterators.hpp
+++ b/source/mijin/util/iterators.hpp
@@ -180,7 +180,7 @@ struct ZippingIterator
 
     ZippingIterator& operator=(const ZippingIterator&) noexcept = default;
 
-    auto operator*() const noexcept
+    decltype(auto) operator*() const noexcept
     {
         return std::tie(*first, *second);
     }