2 files changed, 6 insertions, 5 deletions
diff --git a/src/libstore/download.cc b/src/libstore/download.cc
index 95c7d2255afc..13c665a40ca8 100644
--- a/src/libstore/download.cc
+++ b/src/libstore/download.cc
@@ -243,13 +243,14 @@ ref<Downloader> makeDownloader()
     return make_ref<CurlDownloader>();
 }
 
-Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpack, const Hash & expectedHash)
+Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpack, string name, const Hash & expectedHash)
 {
     auto url = resolveUri(url_);
 
-    string name;
-    auto p = url.rfind('/');
-    if (p != string::npos) name = string(url, p + 1);
+    if (name == "") {
+        auto p = url.rfind('/');
+        if (p != string::npos) name = string(url, p + 1);
+    }
 
     Path expectedStorePath;
     if (expectedHash) {
diff --git a/src/libstore/download.hh b/src/libstore/download.hh
index 1f6098759a2d..08618ba1c95d 100644
--- a/src/libstore/download.hh
+++ b/src/libstore/download.hh
@@ -29,7 +29,7 @@ struct Downloader
 {
     virtual DownloadResult download(string url, const DownloadOptions & options) = 0;
 
-    Path downloadCached(ref<Store> store, const string & url, bool unpack,
+    Path downloadCached(ref<Store> store, const string & url, bool unpack, string name = "",
         const Hash & expectedHash = Hash());
 
     enum Error { NotFound, Forbidden, Misc, Transient };