diff --git a/pkgs/build-support/fetchgit/default.nix b/pkgs/build-support/fetchgit/default.nix
index 3bcda3af1c59..6c5abd592e55 100644
--- a/pkgs/build-support/fetchgit/default.nix
+++ b/pkgs/build-support/fetchgit/default.nix
@@ -148,7 +148,7 @@ lib.makeOverridable (
           inherit outputHash outputHashAlgo;
           outputHashMode = "recursive";
 
-          sparseCheckout = lib.defaultTo (lib.optional (rootDir != "") rootDir) sparseCheckout;
+          sparseCheckout = lib.defaultTo (lib.optional (finalAttrs.rootDir != "") finalAttrs.rootDir) sparseCheckout;
           sparseCheckoutText =
             # Changed to throw on 2023-06-04
             assert (