3 files changed, 13 insertions, 9 deletions

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 081392f3c..6a4a7a035 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1692,6 +1692,7 @@ void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
 {
     string url;
     Hash expectedHash;
+    string name;
 
     state.forceValue(*args[0]);
 
@@ -1700,11 +1701,13 @@ void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
         state.forceAttrs(*args[0], pos);
 
         for (auto & attr : *args[0]->attrs) {
-            string name(attr.name);
-            if (name == "url")
+            string n(attr.name);
+            if (n == "url")
                 url = state.forceStringNoCtx(*attr.value, *attr.pos);
-            else if (name == "sha256")
+            else if (n == "sha256")
                 expectedHash = parseHash16or32(htSHA256, state.forceStringNoCtx(*attr.value, *attr.pos));
+            else if (n == "name")
+                name = state.forceStringNoCtx(*attr.value, *attr.pos);
             else
                 throw EvalError(format("unsupported argument ‘%1%’ to ‘%2%’, at %3%") % attr.name % who % attr.pos);
         }
@@ -1718,7 +1721,7 @@ void fetch(EvalState & state, const Pos & pos, Value * * args, Value & v,
     if (state.restricted && !expectedHash)
         throw Error(format("‘%1%’ is not allowed in restricted mode") % who);
 
-    Path res = makeDownloader()->downloadCached(state.store, url, unpack, expectedHash);
+    Path res = makeDownloader()->downloadCached(state.store, url, unpack, name, expectedHash);
     mkString(v, res, PathSet({res}));
 }
 
diff --git a/src/libstore/download.cc b/src/libstore/download.cc
index 95c7d2255..13c665a40 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 1f6098759..08618ba1c 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 };