diff --git a/src/common/hash.h b/src/common/hash.h
new file mode 100644
index 000000000..964f243b4
--- /dev/null
+++ b/src/common/hash.h
@@ -0,0 +1,29 @@
+/*
+   mkvmerge -- utility for splicing together matroska files
+   from component media subtypes
+
+   Distributed under the GPL v2
+   see the file COPYING for details
+   or visit http://www.gnu.org/copyleft/gpl.html
+
+   Hash/unordered map helper functions
+
+   Written by Moritz Bunkus <moritz@bunkus.org>.
+*/
+
+#ifndef MTX_COMMON_HASH_H
+#define MTX_COMMON_HASH_H
+
+#include <functional>
+
+// Support for hashing all scoped and unscoped enums via their
+// underlying type.
+template<typename Tkey>
+struct std::hash {
+  std::size_t operator()(Tkey const &key) const {
+    using T = typename std::underlying_type<Tkey>::type;
+    return std::hash<T>()(static_cast<T>(key));
+  }
+};
+
+#endif  // MTX_COMMON_HASH_H