diff --git a/src/lib/fmt/SocketAddressFormatter.cxx b/src/lib/fmt/SocketAddressFormatter.cxx
new file mode 100644
index 000000000..bd31f969c
--- /dev/null
+++ b/src/lib/fmt/SocketAddressFormatter.cxx
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// author: Max Kellermann <max.kellermann@gmail.com>
+
+#include "SocketAddressFormatter.hxx"
+#include "net/ToString.hxx"
+
+auto
+fmt::formatter<SocketAddress>::format(SocketAddress address, format_context &ctx)
+  -> format_context::iterator
+{
+	return formatter<string_view>::format(ToString(address), ctx);
+}
diff --git a/src/lib/fmt/SocketAddressFormatter.hxx b/src/lib/fmt/SocketAddressFormatter.hxx
index 7a13bfce4..7020d9083 100644
--- a/src/lib/fmt/SocketAddressFormatter.hxx
+++ b/src/lib/fmt/SocketAddressFormatter.hxx
@@ -4,17 +4,18 @@
 #pragma once
 
 #include "net/SocketAddress.hxx"
-#include "net/ToString.hxx"
 
 #include <fmt/format.h>
 
 #include <concepts>
 
-template<std::convertible_to<SocketAddress> T>
-struct fmt::formatter<T> : formatter<string_view>
+template<>
+struct fmt::formatter<SocketAddress> : formatter<string_view>
+{
+	auto format(SocketAddress address, format_context &ctx) -> format_context::iterator;
+};
+
+template<std::convertible_to<SocketAddress> T>
+struct fmt::formatter<T> : formatter<SocketAddress>
 {
-	template<typename FormatContext>
-	auto format(SocketAddress address, FormatContext &ctx) {
-		return formatter<string_view>::format(ToString(address), ctx);
-	}
 };
diff --git a/src/lib/fmt/meson.build b/src/lib/fmt/meson.build
index f6b0243ee..b0237fd0a 100644
--- a/src/lib/fmt/meson.build
+++ b/src/lib/fmt/meson.build
@@ -11,6 +11,7 @@ endif
 fmt = static_library(
   'fmt',
   'RuntimeError.cxx',
+  'SocketAddressFormatter.cxx',
   'SystemError.cxx',
   include_directories: inc,
   dependencies: libfmt,