diff --git a/pkgs/servers/portmap/default.nix b/pkgs/servers/portmap/default.nix
index df50c3320296..3664bdba661d 100644
--- a/pkgs/servers/portmap/default.nix
+++ b/pkgs/servers/portmap/default.nix
@@ -17,9 +17,9 @@ stdenv.mkDerivation rec {
 
   makeFlags =
    lib.concatStringsSep " "
-     (lib.optional daemonUser "RPCUSER=\"${daemonUser}\""
-      ++ lib.optional daemonUID "DAEMON_UID=${daemonUID}"
-      ++ lib.optional daemonGID "DAEMON_GID=${daemonGID}");
+     (lib.optional (daemonUser != false) "RPCUSER=\"${daemonUser}\""
+      ++ lib.optional (daemonUID != false) "DAEMON_UID=${toString daemonUID}"
+      ++ lib.optional (daemonGID != false) "DAEMON_GID=${toString daemonGID}");
 
   buildInputs = [ tcpWrapper ];
 
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 2dcb1ee8619e..805e656aa99d 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -3656,14 +3656,15 @@ rec {
     inherit fetchurl stdenv apacheHttpd jdk;
   };
 
-  portmap = import ../servers/portmap {
-    inherit fetchurl stdenv lib tcpWrapper;
+  # This function is typically called by the NixOS Upstart job to specify the
+  # right UID/GID for `portmap'.
+  makePortmap = { daemonUser ? false, daemonGID ? false, daemonUID ? false }:
+    (import ../servers/portmap {
+       inherit fetchurl stdenv lib tcpWrapper
+               daemonUser daemonGID daemonUID;
+     });
 
-    # This settings should typically be defined by NixOS Upstart job.
-    daemonUser = false;
-    daemonGID = false;
-    daemonUID = false;
-  };
+  portmap = (makePortmap);
 
   mysql4 = import ../servers/sql/mysql {
     inherit fetchurl stdenv ncurses zlib perl;