diff --git a/default.nix b/default.nix
index 9562383..46373e5 100644
--- a/default.nix
+++ b/default.nix
@@ -1,4 +1,12 @@
-{ sources ? import ./nix/sources.nix {}
+let 
+  overlay = self: super: {
+    nixpkgs = super.nixpkgs-renamed;
+    __fetchers = super.__fetchers // {
+      fetchgit = {url, sha256}@attrs: (import self.nixpkgs {}).fetchgit attrs;
+    };
+  };
+in
+{ sources ? import ./nix/sources.nix { overlays = [overlay]; }
 , pkgs ? import ./nix { inherit sources; }
 }:
 
diff --git a/nix/sources.json b/nix/sources.json
index 76ad832..6fac58d 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -1,5 +1,5 @@
 {
-    "nixpkgs": {
+    "nixpkgs-renamed": {
         "branch": "nixos-19.03",
         "description": "Nixpkgs/NixOS branches that track the Nixpkgs/NixOS channels",
         "homepage": "https://github.com/NixOS/nixpkgs",
@@ -19,8 +19,7 @@
         "repo": "termtosvg",
         "rev": "b97cc0132073111cec37f64c95539e869202ff99",
         "sha256": "1c86622sda98zm3q3dzwmm37i09yca661kn860svl191nqbh2l68",
-        "type": "tarball",
-        "url": "https://github.com/nbedos/termtosvg/archive/b97cc0132073111cec37f64c95539e869202ff99.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+        "type": "fetchgit",
+        "url": "https://github.com/nbedos/termtosvg.git"
     }
 }
diff --git a/script/test b/script/test
index 4fb850b..564422f 100755
--- a/script/test
+++ b/script/test
@@ -1,6 +1,5 @@
 #!/usr/bin/env nix-shell
 #!nix-shell -i bash
-#!nix-shell -I nixpkgs=./nix
 #!nix-shell -p nix
 #!nix-shell --pure
 #!nix-shell --keep SSL_CERT_FILE