diff -ru boost.orig/boost/iostreams/filter/gzip.hpp boost/boost/iostreams/filter/gzip.hpp
--- foo/misc/boost.orig/boost/iostreams/filter/gzip.hpp	2015-07-22 20:58:35.758990022 +0200
+++ foo/misc/boost/boost/iostreams/filter/gzip.hpp	2015-07-22 21:20:50.982997292 +0200
@@ -279,7 +279,7 @@
         boost::iostreams::put(next, static_cast<char>(0xFF & (n >> 24)));
     }
     template<typename Sink>
-    static void write_long(long n, Sink& next, boost::mpl::false_)
+    static void write_long(long, Sink&, boost::mpl::false_)
     {
     }
     template<typename Sink>