diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index da2c6ac366e9..3d44ad0707f7 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -20128,6 +20128,7 @@ in {
     buildInputs = with self; [ unittest2 ];
 
     doCheck = !isPyPy;
+    force-rebuild = 1;  # fix transient test suite error at http://hydra.nixos.org/build/45083762
 
     meta = {
       homepage = https://launchpad.net/pyflakes;