diff --git a/modules/services/logging/syslogd.nix b/modules/services/logging/syslogd.nix
index 7c3e54cadb0..64b158742ec 100644
--- a/modules/services/logging/syslogd.nix
+++ b/modules/services/logging/syslogd.nix
@@ -19,6 +19,8 @@ let
     *.crit                        /var/log/warn
 
     *.*;mail.none;local1.none    -/var/log/messages
+
+    ${config.services.syslogd.extraConfig}
   '';
 
 in
@@ -37,6 +39,14 @@ in
           messages.
         '';
       };
+
+      extraConfig = mkOption {
+        default = "";
+        example = "news.* -/var/log/news";
+        description = ''
+          Additional text appended to <filename>syslog.conf</filename>.
+        '';
+      };
       
     };
     
diff --git a/modules/testing/test-instrumentation.nix b/modules/testing/test-instrumentation.nix
index c404e044f63..5e62c698f27 100644
--- a/modules/testing/test-instrumentation.nix
+++ b/modules/testing/test-instrumentation.nix
@@ -74,7 +74,12 @@ in
 
     # `xwininfo' is used by the test driver to query open windows.
     environment.systemPackages = [ pkgs.xorg.xwininfo ];
-      
+
+    # Send all of /var/log/messages to the serial port (except for
+    # kernel messages through klogd, which already appear on the
+    # serial port).
+    services.syslogd.extraConfig = "*.*,kern.none /dev/ttyS0";
+
   };
 
 }