diff --git a/third_party/nixpkgs/patches/pr122242.patch b/third_party/nixpkgs/patches/pr122242.patch
new file mode 100644
index 0000000000..84e378b416
--- /dev/null
+++ b/third_party/nixpkgs/patches/pr122242.patch
@@ -0,0 +1,37 @@
+From 654997a4ad3032a9e9ef0883b0cccbe233f65079 Mon Sep 17 00:00:00 2001
+From: Luke Granger-Brown <git@lukegb.com>
+Date: Sat, 8 May 2021 20:16:44 +0000
+Subject: [PATCH] python3Packages.hg-evolve: 10.3.0 -> 10.3.1
+
+Fix compatibility with Mercurial 5.8.
+---
+ pkgs/development/python-modules/hg-evolve/default.nix | 6 +++---
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/pkgs/development/python-modules/hg-evolve/default.nix b/pkgs/development/python-modules/hg-evolve/default.nix
+index b7bd002c36786f..46db97a9aedd3d 100644
+--- a/pkgs/development/python-modules/hg-evolve/default.nix
++++ b/pkgs/development/python-modules/hg-evolve/default.nix
+@@ -6,11 +6,11 @@
+ 
+ buildPythonPackage rec {
+   pname = "hg-evolve";
+-  version = "10.3.0";
++  version = "10.3.1";
+ 
+   src = fetchPypi {
+     inherit pname version;
+-    sha256 = "5d7f73fc1c357134ae9b4a3ed2d844ab8e75a4ca1303679a9e150e87617e7bc7";
++    sha256 = "03xwnadpvgna70n6pfxb7xdrszppdqrx5qmkbr1v0jzbh5rnzi6b";
+   };
+ 
+   doCheck = false;
+@@ -18,7 +18,7 @@ buildPythonPackage rec {
+   meta = with lib; {
+     description = "Enables the “changeset evolution” feature of Mercurial core";
+     homepage = "https://www.mercurial-scm.org/doc/evolution/";
+-    maintainers = with maintainers; [ xavierzwirtz ];
++    maintainers = with maintainers; [ xavierzwirtz lukegb ];
+     license = licenses.gpl2Plus;
+   };
+ }
diff --git a/third_party/nixpkgs/patches/series b/third_party/nixpkgs/patches/series
index c4d4698053..7b0adc87b9 100644
--- a/third_party/nixpkgs/patches/series
+++ b/third_party/nixpkgs/patches/series
@@ -2,3 +2,4 @@ various.patch
 patch-cherrypy.patch
 pomerium-fix.patch
 tracker-i686.patch
+pr122242.patch