diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 467ebe7c1e6199366594768bcb4a246091157651..3c8030a2583f5458fb102726a83a6be2d501c049 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -71,5 +71,5 @@ nixpkgs
 
 We pin to a nixos channel release, which isn't directly supported by niv (`issue <https://github.com/nmattia/niv/issues/225>`_).
 Thus, the pin needs to be update manually.
-To do this, copy the ``url`` and ``sha256`` values from PrivateStorageio's `nixpkgs-2105.json <https://whetstone.privatestorage.io/privatestorage/PrivateStorageio/-/blob/develop/nixpkgs-2105.json>`_ into the ``release2015`` entry in ``nix/sources.json``.
+To do this, copy the ``url`` and ``sha256`` values from PrivateStorageio's `nixpkgs-2105.json <https://whetstone.privatestorage.io/privatestorage/PrivateStorageio/-/blob/develop/nixpkgs-2105.json>`_ into the ``release2105`` entry in ``nix/sources.json``.
 When this is deployed as part of Privatestorageio, we use the value pinned there, rather than the pin in this repository.
diff --git a/default.nix b/default.nix
index 7f9b277c7290c3a277c7f80ff194ddabbb32c00b..0e68b6386e993e113260e7cfb72c646947fe6beb 100644
--- a/default.nix
+++ b/default.nix
@@ -1,7 +1,7 @@
 let
   sources = import nix/sources.nix;
 in
-{ pkgs ? import sources.release2015 {}
+{ pkgs ? import sources.release2105 {}
 , pypiData ? sources.pypi-deps-db
 , mach-nix ? import sources.mach-nix { inherit pkgs pypiData; }
 , tahoe-lafs-source ? "tahoe-lafs"
diff --git a/nix/sources.json b/nix/sources.json
index 9ce1d8e0cf1793a5db2e50d82e8758ec645578e7..b294dc6e788e1633112ba3df42109c1497e4a38c 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -35,7 +35,7 @@
         "url": "https://github.com/DavHau/pypi-deps-db/archive/96d01556b4597c022647acbf8c3b58d2a99bc963.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
-    "release2015": {
+    "release2105": {
         "sha256": "112drvixj81vscj8cncmks311rk2ik5gydpd03d3r0yc939zjskg",
         "type": "tarball",
         "url": "https://releases.nixos.org/nixos/21.05/nixos-21.05.3740.ce7a1190a0f/nixexprs.tar.xz",
diff --git a/shell.nix b/shell.nix
index f34fcf949ca84d7b092cf06761aae4f03db8df51..0f661ebc3692fbf6bfe199abc0cbd8fbd6feaa8e 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,7 +1,7 @@
 let
   sources = import nix/sources.nix;
 in
-{ pkgs ? import sources.release2015 {}
+{ pkgs ? import sources.release2105 {}
 , tahoe-lafs-source ? "tahoe-lafs"
 }:
   let
diff --git a/tests.nix b/tests.nix
index 7023c06a296dfd5be2cb3468c789d7038ac25add..e69b4e781e55a7d8a0a02ebe1e57724626a6aaa5 100644
--- a/tests.nix
+++ b/tests.nix
@@ -1,7 +1,7 @@
 let
   sources = import nix/sources.nix;
 in
-{ pkgs ? import sources.release2015 {}
+{ pkgs ? import sources.release2105 {}
 , pypiData ? sources.pypi-deps-db
 , mach-nix ? import sources.mach-nix { inherit pkgs pypiData; }
 , tahoe-lafs-source ? "tahoe-lafs"