Index: subversion/libsvn_ra_serf/ra_serf.h
===================================================================
--- subversion/libsvn_ra_serf/ra_serf.h	(revision 1403730)
+++ subversion/libsvn_ra_serf/ra_serf.h	(working copy)
@@ -56,8 +56,27 @@
 /** Use this to silence compiler warnings about unused parameters. */
 #define UNUSED_CTX(x) ((void)(x))
 
-/** Our User-Agent string. */
-#define USER_AGENT "SVN/" SVN_VER_NUMBER " serf/" \
+#if defined(_WIN32)
+#define USER_AGENT_PLATFORM "Windows"
+#elif __APPLE__
+#define USER_AGENT_PLATFORM "Macintosh"
+#elif __linux__
+#define USER_AGENT_PLATFORM "Linux"
+#elif __FreeBSD__
+#define USER_AGENT_PLATFORM "FreeBSD"
+#elif __NetBSD__
+#define USER_AGENT_PLATFORM "NetBSD"
+#elif __OpenBSD__
+#define USER_AGENT_PLATFORM "OpenBSD"
+#elif __unix__
+#define USER_AGENT_PLATFORM "Unix"
+#else
+#define USER_AGENT_PLATFORM "Unknown"
+#endif
+
+    /** Our User-Agent string. */
+#define USER_AGENT "SVN/" SVN_VER_NUMBER "(" USER_AGENT_PLATFORM ")" \
+                   " serf/" \
                    APR_STRINGIFY(SERF_MAJOR_VERSION) "." \
                    APR_STRINGIFY(SERF_MINOR_VERSION) "." \
                    APR_STRINGIFY(SERF_PATCH_VERSION)