diff --git a/pkgs/top-level/release.nix b/pkgs/top-level/release.nix
index f78152a8931c..ca4c8ce83f3a 100644
--- a/pkgs/top-level/release.nix
+++ b/pkgs/top-level/release.nix
@@ -8,7 +8,11 @@
 
    $ nix-build pkgs/top-level/release.nix -A coreutils.x86_64-linux
 */
-{ nixpkgs ? { outPath = (import ../../lib).cleanSource ../..; revCount = 1234; shortRev = "abcdef"; }
+{ nixpkgs ?
+    if builtins.pathExists ../../.git then
+      fetchGit ../..
+    else
+      { outPath = (import ../../lib).cleanSource ../..; revCount = 1234; shortRev = "abcdef"; }
 , officialRelease ? false
   # The platforms for which we build Nixpkgs.
 , supportedSystems ? [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" ]