diff --git a/flake.lock b/flake.lock
index 9086f0b6..f5913217 100644
--- a/flake.lock
+++ b/flake.lock
@@ -52,16 +52,16 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1599903709,
-        "narHash": "sha256-tinVKY7zRdSXmVOp7BAulNtIb2iP5nvNp5UAxihKXNI=",
+        "lastModified": 1602230526,
+        "narHash": "sha256-3/ucBPYg42P+1ji5/7q227Ek/Eq2C7zeiB9sZl5UpIY=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "252bfe0107587d40092057f338e9ffcf7bbd90cb",
+        "rev": "0b8799ecaaf0dc6b4c11583a3c96ca5b40fcfdfb",
         "type": "github"
       },
       "original": {
         "id": "nixpkgs",
-        "ref": "nixos-20.03",
+        "ref": "nixos-20.09",
         "type": "indirect"
       }
     },
diff --git a/flake.nix b/flake.nix
index 75b8b574..7756916b 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,7 +1,7 @@
 {
   description = "A Nix-based continuous build system";
 
-  inputs.nixpkgs.url = "nixpkgs/nixos-20.03";
+  inputs.nixpkgs.url = "nixpkgs/nixos-20.09";
 
   outputs = { self, nixpkgs, nix }:
     let
@@ -162,7 +162,7 @@
 
           buildInputs =
             [ makeWrapper autoconf automake libtool unzip nukeReferences pkgconfig libpqxx
-              gitAndTools.topGit mercurial darcs subversion bazaar openssl bzip2 libxslt
+              gitAndTools.topGit mercurial darcs subversion breezy openssl bzip2 libxslt
               perlDeps perl final.nix
               boost
               postgresql_11
@@ -177,7 +177,7 @@
 
           hydraPath = lib.makeBinPath (
             [ subversion openssh final.nix coreutils findutils pixz
-              gzip bzip2 lzma gnutar unzip git gitAndTools.topGit mercurial darcs gnused bazaar
+              gzip bzip2 lzma gnutar unzip git gitAndTools.topGit mercurial darcs gnused breezy
             ] ++ lib.optionals stdenv.isLinux [ rpm dpkg cdrkit ] );
 
           configureFlags = [ "--with-docbook-xsl=${docbook_xsl}/xml/xsl/docbook" ];
@@ -202,6 +202,8 @@
           preCheck = ''
             patchShebangs .
             export LOGNAME=''${LOGNAME:-foo}
+            # set $HOME for bzr so it can create its trace file
+            export HOME=$(mktemp -d)
           '';
 
           postInstall = ''