diff --git a/libs/util/include/psemek/util/uuid.hpp b/libs/util/include/psemek/util/uuid.hpp
index 3987444f..cef791de 100644
--- a/libs/util/include/psemek/util/uuid.hpp
+++ b/libs/util/include/psemek/util/uuid.hpp
@@ -6,6 +6,8 @@
 #include <cstdint>
 #include <string_view>
 #include <iostream>
+#include <bit>
+#include <format>
 
 namespace psemek::util
 {
@@ -44,6 +46,8 @@ namespace psemek::util
 		return uuid;
 	}
 
+	// Make a version 3 UUID (name-based, using MD5)
+	// NB: the namespace UUID is omitted (empty)
 	// TODO: use SHA-1 or something like that?
 	constexpr uuid make_uuid(std::string_view str)
 	{
@@ -76,4 +80,21 @@ namespace std
 		}
 	};
 
+	template <typename Char>
+	struct formatter<::psemek::util::uuid, Char>
+	{
+		constexpr auto parse(std::format_parse_context & ctx)
+		{
+			return ctx.begin();
+		}
+
+		template <typename FormatContext>
+		auto format(::psemek::util::uuid const & uuid, FormatContext & ctx) const
+		{
+			auto x0 = std::byteswap(uuid[0]);
+			auto x1 = std::byteswap(uuid[1]);
+			return std::format_to(ctx.out(), "{:08x}-{:04x}-{:04x}-{:04x}-{:012x}", x0 & 0xffffffffull, (x0 >> 4) & 0xfffful, (x0 >> 6) & 0xfffful, x1 & 0xfffful, (x1 >> 2) & 0xffffffffffffull);
+		}
+	};
+
 }
diff --git a/libs/util/source/uuid.cpp b/libs/util/source/uuid.cpp
index 1505ebf6..8c87fdd6 100644
--- a/libs/util/source/uuid.cpp
+++ b/libs/util/source/uuid.cpp
@@ -7,16 +7,19 @@ namespace psemek::util
 
 	std::ostream & operator << (std::ostream & os, uuid const & uuid)
 	{
+		auto x0 = std::byteswap(uuid[0]);
+		auto x1 = std::byteswap(uuid[1]);
+
 		os << std::hex << std::setfill('0') << std::left;
-		os << std::setw(8)  <<  (uuid[0] & 0x00000000ffffffffull);
+		os << std::setw(8)  <<  (x0 & 0xffffffffull);
 		os << std::setw(1) << '-';
-		os << std::setw(4)  << ((uuid[0] & 0x0000ffff00000000ull) >> 32);
+		os << std::setw(4)  << ((x0 >> 4) & 0xfffful);
 		os << std::setw(1) << '-';
-		os << std::setw(4)  << ((uuid[0] & 0xffff000000000000ull) >> 48);
+		os << std::setw(4)  << ((x0 >> 6) & 0xfffful);
 		os << std::setw(1) << '-';
-		os << std::setw(4)  <<  (uuid[1] & 0x000000000000ffffull);
+		os << std::setw(4)  <<  (x1 & 0xfffful);
 		os << std::setw(1) << '-';
-		os << std::setw(12) << ((uuid[1] & 0xffffffffffff0000ull) >> 16);
+		os << std::setw(12) << ((x1 >> 2) & 0xffffffffffffull);
 
 		return os;
 	}