diff --git a/pkgs/build-support/fetchgit/default.nix b/pkgs/build-support/fetchgit/default.nix
index 990e6c6f9889..94d1bf796b40 100644
--- a/pkgs/build-support/fetchgit/default.nix
+++ b/pkgs/build-support/fetchgit/default.nix
@@ -267,7 +267,7 @@ lib.makeOverridable (
             // meta.identifiers or { };
           };
 
-          env = {
+          env = derivationArgs.env or { } // {
             NIX_PREFETCH_GIT_CHECKOUT_HOOK = finalAttrs.postCheckout;
           };