diff --git a/nixos/modules/security/ca.nix b/nixos/modules/security/ca.nix
index 849530238e7e..67469be18b41 100644
--- a/nixos/modules/security/ca.nix
+++ b/nixos/modules/security/ca.nix
@@ -4,10 +4,16 @@ with lib;
 
 let
 
+  cfg = config.security.pki;
+
+  cacertPackage = pkgs.cacert.override {
+    blacklist = cfg.caCertificateBlacklist;
+  };
+
   caCertificates = pkgs.runCommand "ca-certificates.crt"
     { files =
-        config.security.pki.certificateFiles ++
-        [ (builtins.toFile "extra.crt" (concatStringsSep "\n" config.security.pki.certificates)) ];
+        cfg.certificateFiles ++
+        [ (builtins.toFile "extra.crt" (concatStringsSep "\n" cfg.certificates)) ];
      }
     ''
       cat $files > $out
@@ -52,11 +58,27 @@ in
       '';
     };
 
+    security.pki.caCertificateBlacklist = mkOption {
+      type = types.listOf types.str;
+      default = [];
+      example = [
+        "WoSign" "WoSign China"
+        "CA WoSign ECC Root"
+        "Certification Authority of WoSign G2"
+      ];
+      description = ''
+        A list of blacklisted CA certificate names that won't be imported from
+        the Mozilla Trust Store into
+        <filename>/etc/ssl/certs/ca-certificates.crt</filename>. Use the
+        names from that file.
+      '';
+    };
+
   };
 
   config = {
 
-    security.pki.certificateFiles = [ "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt" ];
+    security.pki.certificateFiles = [ "${cacertPackage}/etc/ssl/certs/ca-bundle.crt" ];
 
     # NixOS canonical location + Debian/Ubuntu/Arch/Gentoo compatibility.
     environment.etc."ssl/certs/ca-certificates.crt".source = caCertificates;
diff --git a/pkgs/data/misc/cacert/default.nix b/pkgs/data/misc/cacert/default.nix
index 3ce6dc81a396..5095fce8958e 100644
--- a/pkgs/data/misc/cacert/default.nix
+++ b/pkgs/data/misc/cacert/default.nix
@@ -1,25 +1,49 @@
-{ stdenv, nss, curl, perl }:
+{ stdenv, fetchurl, writeText, nss, python
+, blacklist ? []
+, includeEmail ? false
+}:
+
+with stdenv.lib;
+
+let
+
+  certdata2pem = fetchurl {
+    name = "certdata2pem.py";
+    url = "https://anonscm.debian.org/cgit/collab-maint/ca-certificates.git/plain/mozilla/certdata2pem.py?h=debian/20160104";
+    sha256 = "0bw11mgfrf19qziyvdnq22kirp0nn54lfsanrg5h6djs6ig1c2im";
+  };
+
+in
 
 stdenv.mkDerivation rec {
   name = "nss-cacert-${nss.version}";
 
   src = nss.src;
 
-  postPatch = ''
-    unpackFile ${curl.src};
+  nativeBuildInputs = [ python ];
 
-    # Remove dependency on LWP, curl is enough. Also, since curl here
-    # is working on a local file it will not actually get a 200 OK, so
-    # remove that expectation.
-    substituteInPlace curl-*/lib/mk-ca-bundle.pl \
-      --replace 'use LWP::UserAgent;' "" \
-      --replace ' && $out[0] == 200' ""
+  configurePhase = ''
+    ln -s nss/lib/ckfw/builtins/certdata.txt
+
+    cat << EOF > blacklist.txt
+    ${concatStringsSep "\n" (map (c: ''"${c}"'') blacklist)}
+    EOF
+
+    cp ${certdata2pem} certdata2pem.py
+    ${optionalString includeEmail ''
+      # Disable CAs used for mail signing
+      substituteInPlace certdata2pem.py --replace \[\'CKA_TRUST_EMAIL_PROTECTION\'\] '''
+    ''}
   '';
 
-  nativeBuildInputs = [ curl perl ];
-
   buildPhase = ''
-    perl curl-*/lib/mk-ca-bundle.pl -d "file://$(pwd)/nss/lib/ckfw/builtins/certdata.txt" ca-bundle.crt
+    python certdata2pem.py | grep -vE '^(!|UNTRUSTED)'
+
+    for cert in *.crt; do
+      echo $cert | cut -d. -f1 | sed -e 's,_, ,g' >> ca-bundle.crt
+      cat $cert >> ca-bundle.crt
+      echo >> ca-bundle.crt
+    done
   '';
 
   installPhase = ''
@@ -27,10 +51,10 @@ stdenv.mkDerivation rec {
     cp -v ca-bundle.crt $out/etc/ssl/certs
   '';
 
-  meta = with stdenv.lib; {
+  meta = {
     homepage = http://curl.haxx.se/docs/caextract.html;
     description = "A bundle of X.509 certificates of public Certificate Authorities (CA)";
     platforms = platforms.all;
-    maintainers = with maintainers; [ wkennington ];
+    maintainers = with maintainers; [ wkennington fpletz ];
   };
 }