diff --git a/src/libexpr/primops/fetchGit.cc b/src/libexpr/primops/fetchGit.cc
index 5d6249e56..b46d2f258 100644
--- a/src/libexpr/primops/fetchGit.cc
+++ b/src/libexpr/primops/fetchGit.cc
@@ -85,6 +85,8 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
     if (rev != "" && !std::regex_match(rev, revRegex))
         throw Error("invalid Git revision '%s'", rev);
 
+    deletePath(getCacheDir() + "/nix/git");
+
     Path cacheDir = getCacheDir() + "/nix/gitv2/" + hashString(htSHA256, uri).to_string(Base32, false);
 
     if (!pathExists(cacheDir)) {
@@ -92,9 +94,7 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
         runProgram("git", true, { "init", "--bare", cacheDir });
     }
 
-    std::string localRef = hashString(htSHA256, fmt("%s-%s", uri, *ref)).to_string(Base32, false);
-
-    Path localRefFile = cacheDir + "/refs/heads/" + localRef;
+    Path localRefFile = cacheDir + "/refs/heads/" + *ref;
 
     bool doFetch;
     time_t now = time(0);
@@ -124,7 +124,7 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
 
         // FIXME: git stderr messes up our progress indicator, so
         // we're using --quiet for now. Should process its stderr.
-        runProgram("git", true, { "-C", cacheDir, "fetch", "--quiet", "--force", "--", uri, *ref + ":" + localRef });
+        runProgram("git", true, { "-C", cacheDir, "fetch", "--quiet", "--force", "--", uri, fmt("%s:%s", *ref, *ref) });
 
         struct timeval times[2];
         times[0].tv_sec = now;