diff --git a/.travis.yml b/.travis.yml
index ce3a66bec..ac4caa6a9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -121,7 +121,6 @@ install:
       brew update > /dev/null ;
       brew install colormake ccache ;
       brew outdated "pkg-config" || brew upgrade "pkg-config" ;
-      brew outdated "zlib" || brew upgrade "zlib" ;
       # libtorrent-rasterbar 1.0.9
       brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/477d5060fa093883204d70323965375353e03084/Formula/libtorrent-rasterbar.rb ;
 
diff --git a/configure b/configure
index 901f8426f..2c72cb291 100755
--- a/configure
+++ b/configure
@@ -5101,7 +5101,7 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
 int
 main ()
 {
-boost::system::system_category
+boost::system::error_category *a = 0;
   ;
   return 0;
 }
diff --git a/m4/ax_boost_system.m4 b/m4/ax_boost_system.m4
index c4c45559d..43570a513 100644
--- a/m4/ax_boost_system.m4
+++ b/m4/ax_boost_system.m4
@@ -31,7 +31,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 17
+#serial 18
 
 AC_DEFUN([AX_BOOST_SYSTEM],
 [
@@ -68,9 +68,10 @@ AC_DEFUN([AX_BOOST_SYSTEM],
 					   ax_cv_boost_system,
         [AC_LANG_PUSH([C++])
 			 CXXFLAGS_SAVE=$CXXFLAGS
+			 CXXFLAGS=
 
 			 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[@%:@include <boost/system/error_code.hpp>]],
-                                   [[boost::system::system_category]])],
+				    [[boost::system::error_category *a = 0;]])],
                    ax_cv_boost_system=yes, ax_cv_boost_system=no)
 			 CXXFLAGS=$CXXFLAGS_SAVE
              AC_LANG_POP([C++])