diff --git a/src/libfetchers/github.cc b/src/libfetchers/github.cc
index 1ca639419..8100afe4d 100644
--- a/src/libfetchers/github.cc
+++ b/src/libfetchers/github.cc
@@ -98,6 +98,10 @@ struct GitArchiveInputScheme : InputScheme
         if (ref) input.attrs.insert_or_assign("ref", *ref);
         if (host_url) input.attrs.insert_or_assign("host", *host_url);
 
+        auto narHash = url.query.find("narHash");
+        if (narHash != url.query.end())
+            input.attrs.insert_or_assign("narHash", narHash->second);
+
         return input;
     }
 
@@ -135,10 +139,13 @@ struct GitArchiveInputScheme : InputScheme
         assert(!(ref && rev));
         if (ref) path += "/" + *ref;
         if (rev) path += "/" + rev->to_string(HashFormat::Base16, false);
-        return ParsedURL {
+        auto url = ParsedURL {
             .scheme = std::string { schemeName() },
             .path = path,
         };
+        if (auto narHash = input.getNarHash())
+            url.query.insert_or_assign("narHash", narHash->to_string(HashFormat::SRI, true));
+        return url;
     }
 
     Input applyOverrides(
diff --git a/tests/nixos/github-flakes.nix b/tests/nixos/github-flakes.nix
index a51689445..6f8a5b9d8 100644
--- a/tests/nixos/github-flakes.nix
+++ b/tests/nixos/github-flakes.nix
@@ -58,7 +58,7 @@ let
       mkdir -p $out/{commits,tarball}
 
       # Setup https://docs.github.com/en/rest/commits/commits#get-a-commit
-      echo '{"sha": "${private-flake-rev}"}' > $out/commits/HEAD
+      echo '{"sha": "${private-flake-rev}", "commit": {"tree": {"sha": "ffffffffffffffffffffffffffffffffffffffff"}}}' > $out/commits/HEAD
 
       # Setup tarball download via API
       dir=private-flake
@@ -72,7 +72,7 @@ let
       mkdir -p $out/commits
 
       # Setup https://docs.github.com/en/rest/commits/commits#get-a-commit
-      echo '{"sha": "${nixpkgs.rev}"}' > $out/commits/HEAD
+      echo '{"sha": "${nixpkgs.rev}", "commit": {"tree": {"sha": "ffffffffffffffffffffffffffffffffffffffff"}}}' > $out/commits/HEAD
     '';
 
   archive = pkgs.runCommand "nixpkgs-flake" {}