diff --git a/pkgs/development/libraries/libvirt/default.nix b/pkgs/development/libraries/libvirt/default.nix
index 27e67866fe3..888cf833eab 100644
--- a/pkgs/development/libraries/libvirt/default.nix
+++ b/pkgs/development/libraries/libvirt/default.nix
@@ -1,16 +1,12 @@
 { stdenv, fetchurl, pkgconfig, libxml2, gnutls, devicemapper, perl, python
 , iproute, iptables, readline, lvm2, utillinux, udev, libpciaccess, gettext
 , libtasn1, ebtables, libgcrypt, yajl, makeWrapper, pmutils, libcap_ng
-, dnsmasq, libnl, libpcap, libxslt, xhtml1, numad, numactl
-, pythonPackages, perlPackages
+, dnsmasq, libnl, libpcap, libxslt, xhtml1, numad, numactl, perlPackages
 }:
 
-let version = "1.2.19"; in
-
-assert version == pythonPackages.libvirt.version;
-
 stdenv.mkDerivation rec {
   name = "libvirt-${version}";
+  version = "1.2.19";
 
   src = fetchurl {
     url = "http://libvirt.org/sources/${name}.tar.gz";
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index eab64615606..0bcc1714982 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -21724,9 +21724,10 @@ in modules // {
     };
   };
 
-  libvirt = pkgs.stdenv.mkDerivation rec {
+  libvirt = let
+    version = "1.2.18";
+  in assert version == pkgs.libvirt.version; pkgs.stdenv.mkDerivation rec {
     name = "libvirt-python-${version}";
-    version = "1.2.19";
 
     src = pkgs.fetchurl {
       url = "http://libvirt.org/sources/python/${name}.tar.gz";