diff --git a/modules/services/mail/postfix.nix b/modules/services/mail/postfix.nix
index 939260632c9..03c77885d06 100644
--- a/modules/services/mail/postfix.nix
+++ b/modules/services/mail/postfix.nix
@@ -287,7 +287,15 @@ in
 
         daemonType = "none";
 
-        respawn = false;
+        respawn = true;
+
+        script = ''
+          while ${pkgs.procps}/bin/ps `${pkgs.coreutils}/bin/cat /var/postfix/queue/pid/master.pid` |
+            grep -q postfix
+          do
+            ${pkgs.coreutils}/bin/sleep 1m
+          done
+        '';
 
         preStart =
           ''
diff --git a/modules/system/upstart/upstart.nix b/modules/system/upstart/upstart.nix
index 3110f376eec..cb3975e694c 100644
--- a/modules/system/upstart/upstart.nix
+++ b/modules/system/upstart/upstart.nix
@@ -21,6 +21,7 @@ let
   makeJob = job:
 
     let
+      hasMain = job.script != "" || job.exec != "";
 
       jobText =
         let log = "/var/log/upstart/${job.name}"; in
@@ -77,12 +78,14 @@ let
           ${optionalString job.task "task"}
           ${optionalString (!job.task && job.respawn) "respawn"}
 
-          ${optionalString (job.preStop != "") ''
+          ${ # preStop is run only if there is exec or script.
+             # (upstart 0.6.5, job.c:562)
+            optionalString (job.preStop != "") (assert hasMain; ''
             pre-stop script
               exec >> ${log} 2>&1
               ${job.preStop}
             end script
-          ''}
+          '')}
 
           ${optionalString (job.postStop != "") ''
             post-stop script