diff --git a/Formula/bup.rb b/Formula/bup.rb
index f9c40380ce9d..de289735e9d4 100644
--- a/Formula/bup.rb
+++ b/Formula/bup.rb
@@ -3,6 +3,7 @@ class Bup < Formula
   homepage "https://github.com/bup/bup"
   url "https://github.com/bup/bup/archive/0.30.tar.gz"
   sha256 "5238f045c220278a165fff528ea32288f2752db2e1ac15704e849b71cddda0b2"
+  revision 1
   head "https://github.com/bup/bup.git"
 
   bottle do
@@ -13,16 +14,11 @@ class Bup < Formula
   end
 
   depends_on "pandoc" => :build
-  depends_on "python@2" # does not support Python 3
-
-  resource "backports_abc" do
-    url "https://files.pythonhosted.org/packages/68/3c/1317a9113c377d1e33711ca8de1e80afbaf4a3c950dd0edfaf61f9bfe6d8/backports_abc-0.5.tar.gz"
-    sha256 "033be54514a03e255df75c5aee8f9e672f663f93abb723444caec8fe43437bde"
-  end
+  uses_from_macos "python@2"
 
   resource "certifi" do
-    url "https://files.pythonhosted.org/packages/41/b6/4f0cefba47656583217acd6cd797bc2db1fede0d53090fdc28ad2c8e0716/certifi-2018.10.15.tar.gz"
-    sha256 "6d58c986d22b038c8c0df30d639f23a3e6d172a05c3583e766f4c0b785c0986a"
+    url "https://files.pythonhosted.org/packages/41/bf/9d214a5af07debc6acf7f3f257265618f1db242a3f8e49a9b516f24523a6/certifi-2019.11.28.tar.gz"
+    sha256 "25b64c7da4cd7479594d035c08c2d809eb4aab3a26e5a990ea98cc450c320f1f"
   end
 
   resource "singledispatch" do
@@ -31,13 +27,13 @@ class Bup < Formula
   end
 
   resource "six" do
-    url "https://files.pythonhosted.org/packages/16/d8/bc6316cf98419719bd59c91742194c111b6f2e85abac88e496adefaf7afe/six-1.11.0.tar.gz"
-    sha256 "70e8a77beed4562e7f14fe23a786b54f6296e34344c23bc42f07b15018ff98e9"
+    url "https://files.pythonhosted.org/packages/94/3e/edcf6fef41d89187df7e38e868b2dd2182677922b600e880baad7749c865/six-1.13.0.tar.gz"
+    sha256 "30f610279e8b2578cab6db20741130331735c781b56053c59c4076da27f06b66"
   end
 
   resource "tornado" do
-    url "https://files.pythonhosted.org/packages/e6/78/6e7b5af12c12bdf38ca9bfe863fcaf53dc10430a312d0324e76c1e5ca426/tornado-5.1.1.tar.gz"
-    sha256 "4e5158d97583502a7e2739951553cbd88a72076f152b4b11b64b9a10c4c49409"
+    url "https://files.pythonhosted.org/packages/30/78/2d2823598496127b21423baffaa186b668f73cd91887fcef78b6eade136b/tornado-6.0.3.tar.gz"
+    sha256 "c845db36ba616912074c5b1ee897f8e0124df269468f25e4fe21fe72f6edd7a9"
   end
 
   def install