diff --git a/README.md b/README.md
index 5561bd2..4c125da 100644
--- a/README.md
+++ b/README.md
@@ -15,9 +15,6 @@ SNM branch corresponding to your NixOS version.
    - Use the [SNM branch `nixos-19.09`](https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/tree/nixos-19.09)
 * For NixOS unstable
    - Use the [SNM branch `master`](https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/tree/master)
-   - This branch is currently still supporting the NixOS release 20.03
-     but we could remove this support on any NixOS unstable breaking
-     change.
 
 [Subscribe to SNM Announcement List](https://www.freelists.org/list/snm)
 This is a very low volume list where new releases of SNM are announced, so you
diff --git a/nix/sources.json b/nix/sources.json
index 7a4d382..abd6979 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -1,16 +1,4 @@
 {
-    "nixpkgs-20.03": {
-        "branch": "nixos-20.03",
-        "description": "A read-only mirror of NixOS/nixpkgs tracking the released channels. Send issues and PRs to",
-        "homepage": "https://github.com/NixOS/nixpkgs",
-        "owner": "NixOS",
-        "repo": "nixpkgs-channels",
-        "rev": "274831839c4f2622019a35d773d4ee588a08c311",
-        "sha256": "1dn0cv8ciq83c75hjqlqljjmsns60wqyijx9hzm3j8jvfxm4gzgk",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs-channels/archive/274831839c4f2622019a35d773d4ee588a08c311.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
     "nixpkgs-unstable": {
         "branch": "nixos-unstable",
         "description": "A read-only mirror of NixOS/nixpkgs tracking the released channels. Send issues and PRs to",
diff --git a/tests/default.nix b/tests/default.nix
index e78a96f..d94300e 100644
--- a/tests/default.nix
+++ b/tests/default.nix
@@ -27,7 +27,6 @@ let
   };
 
   releaseNames = [
-    "nixpkgs-20.03"
     "nixpkgs-unstable"
   ];