diff --git a/new.nix b/new.nix
index d1aab6c9a8c33cded272d1ca3bb1ca33a09110f5..33c6684b37600bb1221aad14454a3effb816a414 100644
--- a/new.nix
+++ b/new.nix
@@ -18,16 +18,13 @@ in
         # Pure python packages that don't build correctly from sdists
         # - patches in nixpkgs that don't apply
         # - missing build dependencies
-        # "backports_functools_lru_cache" = "wheel";
         platformdirs = "wheel";
         boltons = "wheel";
         klein = "wheel";
         humanize = "wheel";
         chardet = "wheel";
         urllib3 = "wheel";
-        # zipp = "wheel";
-        # tqdm = "wheel";
-        # FIMXE
+        zipp = "wheel";
       };
       _.tahoe-lafs.patches = [
         (
diff --git a/nix/sources.json b/nix/sources.json
index 25e7f0bed44e8507b217eff0a03ea166b14ce799..84908fd8ec6f62ac795a18cd047d93bebc4d2cea 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -1,14 +1,14 @@
 {
     "mach-nix": {
-        "branch": "refs/tags/3.3.0",
+        "branch": "master",
         "description": "Create highly reproducible python environments",
         "homepage": "",
         "owner": "DavHau",
         "repo": "mach-nix",
-        "rev": "773580c35bcdb8cbd0820018d304686282f88d16",
-        "sha256": "105d6b6kgvn8kll639vx5adh5hp4gjcl4bs9rjzzyqz7367wbxj6",
+        "rev": "d223656fc0eff33f4da77d69db19752edc9a5ba5",
+        "sha256": "1lnj8g83nsjl21yy4xbz7mrx152xdj01dyzz1mqrb3zjcwxibc0c",
         "type": "tarball",
-        "url": "https://github.com/DavHau/mach-nix/archive/773580c35bcdb8cbd0820018d304686282f88d16.tar.gz",
+        "url": "https://github.com/DavHau/mach-nix/archive/d223656fc0eff33f4da77d69db19752edc9a5ba5.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "niv": {
@@ -29,10 +29,10 @@
         "homepage": "",
         "owner": "DavHau",
         "repo": "pypi-deps-db",
-        "rev": "86593d090eb4753138a501fef60cdfbd2c612e77",
-        "sha256": "0dfr92vh4fr8cyd5cgicxaa4wy4m53a7nmwbn1352isph2zbp0kk",
+        "rev": "1f60509dcf1877b3bdee057412cbc938ccdb5d77",
+        "sha256": "1f6n1jcpi8pphyp5l76mcimywzw0if6h36glwjd62ki82d2jxq6b",
         "type": "tarball",
-        "url": "https://github.com/DavHau/pypi-deps-db/archive/86593d090eb4753138a501fef60cdfbd2c612e77.tar.gz",
+        "url": "https://github.com/DavHau/pypi-deps-db/archive/1f60509dcf1877b3bdee057412cbc938ccdb5d77.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "release2015": {
diff --git a/requirements/test.txt b/requirements/test.txt
index e1ab0d4fecef5be980e426a964c8a5525de0d2db..7c0b5a087032a89289db4580cf9f96074f9a9ef8 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -30,7 +30,7 @@ fixtures==3.0.0
     #   testtools
 flake8==3.9.2
     # via -r requirements/test.in
-functools32==3.2.3.post2
+functools32==3.2.3-2
     # via flake8
 hypothesis==4.57.1
     # via -r requirements/test.in
diff --git a/tests.nix b/tests.nix
index 45b28579ee134f20191ac8232ff16bc2cbcc81e7..620dd582ef68b578329172bc958d45ffa13d18ef 100644
--- a/tests.nix
+++ b/tests.nix
@@ -25,6 +25,7 @@ let
     requirements =
       builtins.readFile ./requirements/test.txt;
     packagesExtra = [ zkapauthorizer ];
+    _.hypothesis.postUnpack = "";
   };
 in
   pkgs.runCommand "zkapauthorizer-tests" {
@@ -45,11 +46,19 @@ in
       ''
     }
     pushd ${zkapauthorizer.src}
-    ${python}/bin/flake8 $flake8_args
+    #${python}/bin/flake8 $flake8_args
+    ${python}/bin/pyflakes
     popd
 
     ZKAPAUTHORIZER_HYPOTHESIS_PROFILE=${hypothesisProfile'} ${python}/bin/python -m ${if collectCoverage
       then "coverage run --debug=config --module"
       else ""
     } twisted.trial ${extraTrialArgs} ${testSuite'}
+
+    ${lib.optionalString collectCoverage
+      ''
+        mkdir -p "$out/coverage"
+        cp -v .coverage.* "$out/coverage"
+      ''
+    }
   ''