diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 2e4b72c9f..c167444b0 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -161,6 +161,7 @@ static void fetchTree(
             fetchers::Attrs attrs;
             attrs.emplace("type", "git");
             attrs.emplace("url", fixGitURL(url));
+            attrs.emplace("exportIgnore", Explicit<bool>{true});
             input = fetchers::Input::fromAttrs(std::move(attrs));
         } else {
             if (!experimentalFeatureSettings.isEnabled(Xp::Flakes))