diff --git a/nix/ci.nix b/nix/ci.nix
index c574b1a..5a529e4 100644
--- a/nix/ci.nix
+++ b/nix/ci.nix
@@ -5,7 +5,6 @@ let
   ;
   in
   dimension "Nixpkgs" {
-    "nixpkgs-19_03" = sources."nixos-19.03";
     "nixpkgs-19_09" = sources."nixos-19.09";
     "nixpkgs-21_05" = sources."nixos-21.05";
   } (_key: nixpkgs:
diff --git a/nix/sources.json b/nix/sources.json
index 56cbf2a..5aafd37 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -11,18 +11,6 @@
         "url": "https://github.com/nmattia/niv/archive/5e9671a9a87c240b1c6ce981d04ad23ba4291451.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
-    "nixos-19.03": {
-        "branch": "nixos-19.03",
-        "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": "2dfae8e22fde5032419c3027964c406508332974",
-        "sha256": "0293j9wib78n5nspywrmd9qkvcqq2vcrclrryxqnaxvj3bs1c0vj",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs-channels/archive/2dfae8e22fde5032419c3027964c406508332974.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
     "nixos-19.09": {
         "branch": "nixos-19.09",
         "description": "A read-only mirror of NixOS/nixpkgs tracking the released channels. Send issues and PRs to",