diff --git a/pkgs/development/ruby-modules/gem/default.nix b/pkgs/development/ruby-modules/gem/default.nix
index b0abb2c54fc5..c881d4eb4744 100644
--- a/pkgs/development/ruby-modules/gem/default.nix
+++ b/pkgs/development/ruby-modules/gem/default.nix
@@ -63,7 +63,6 @@ let
     else if type == "git" then
       fetchgit {
         inherit (attrs.source) url rev sha256 fetchSubmodules;
-        leaveDotGit = true;
       }
     else if type == "url" then
       fetchurl attrs.source
@@ -95,6 +94,7 @@ stdenv.mkDerivation ((builtins.removeAttrs attrs ["source"]) // {
 
   inherit src;
 
+
   unpackPhase = attrs.unpackPhase or ''
     runHook preUnpack
 
@@ -142,6 +142,12 @@ stdenv.mkDerivation ((builtins.removeAttrs attrs ["source"]) // {
       gempkg=$(echo "$output" | grep -oP 'File: \K(.*)')
 
       echo "gem package built: $gempkg"
+    elif [[ "$type" == "git" ]]; then
+      git init
+      # remove variations to improve the likelihood of a bit-reproducible output
+      rm -rf .git/logs/ .git/hooks/ .git/index .git/FETCH_HEAD .git/ORIG_HEAD .git/refs/remotes/origin/HEAD .git/config
+      # support `git ls-files`
+      git add .
     fi
 
     runHook postBuild