diff --git a/default.nix b/default.nix
index c4a45b5..781f739 100644
--- a/default.nix
+++ b/default.nix
@@ -59,7 +59,7 @@
 }:
 let
   inherit (lib) optionalAttrs optionalString;
-  inherit (import ./fetch-overrides.nix) extraPins extraUrls forceDeepClone;
+  inherit (import ./fetch-overrides.nix) extraPins extraUrls forceDeepCloneDomains;
 
   # Step 1: determine which Emacs packages to pull in.
   #
@@ -261,7 +261,9 @@ let
             }
             // optionalAttrs (p ? recipe.branch) { ref = p.recipe.branch; }
             // optionalAttrs (p ? recipe.depth) { shallow = p.recipe.depth == 1; }
-            // optionalAttrs (forceDeepClone.${url} or false) { shallow = false; };
+            // optionalAttrs (lib.any (d: lib.hasPrefix d url) forceDeepCloneDomains) {
+              shallow = false;
+            };
             src =
               if experimentalFetchTree
               then builtins.fetchTree (
diff --git a/fetch-overrides.nix b/fetch-overrides.nix
index e7f978e..fd96189 100644
--- a/fetch-overrides.nix
+++ b/fetch-overrides.nix
@@ -55,8 +55,9 @@
     git-commit = "ea0f07e54967197ac0b072a69ba314314a4080c1";
   };
 
-  # Repositories for which to force `shallow = false`.
-  forceDeepClone = {
-      "https://git.notmuchmail.org/git/notmuch" = true;
-  };
+  # Domains for which to force `shallow = false`.
+  forceDeepCloneDomains = [
+      "https://git.notmuchmail.org/"
+      "https://git.savannah.gnu.org/"
+  ];
 }