diff --git a/pkgs/development/erlang-modules/build-hex.nix b/pkgs/development/erlang-modules/build-hex.nix
index 6a1f4172bbd..6fd8983d411 100644
--- a/pkgs/development/erlang-modules/build-hex.nix
+++ b/pkgs/development/erlang-modules/build-hex.nix
@@ -16,12 +16,7 @@ stdenv.mkDerivation (attrs // {
   buildInputs = buildInputs ++ [ erlang rebar3 openssl libyaml ];
 
   postPatch = let
-    registrySnapshot = fetchFromGitHub {
-      owner = "gleber";
-      repo = "hex-pm-registry-snapshots";
-      rev = "48147b0";
-      sha256 = "0ibfnhrhbka4n6wkhs99fpy3sjab54ip37jgvx2hcfhfr4pxhbxw";
-    };
+    registrySnapshot = import ./registrySnapshot.nix { inherit fetchFromGitHub; };
   in ''
     rm -f rebar rebar3
     if [ -e "src/${name}.app.src" ]; then
diff --git a/pkgs/development/erlang-modules/registrySnapshot.nix b/pkgs/development/erlang-modules/registrySnapshot.nix
new file mode 100644
index 00000000000..cca3dd0c56b
--- /dev/null
+++ b/pkgs/development/erlang-modules/registrySnapshot.nix
@@ -0,0 +1,8 @@
+{ fetchFromGitHub }:
+
+fetchFromGitHub {
+  owner = "gleber";
+  repo = "hex-pm-registry-snapshots";
+  rev = "48147b0";
+  sha256 = "0ibfnhrhbka4n6wkhs99fpy3sjab54ip37jgvx2hcfhfr4pxhbxw";
+}