diff --git a/src/hydra-queue-runner/Makefile.am b/src/hydra-queue-runner/Makefile.am
index 9303d7d5..3b5b48a2 100644
--- a/src/hydra-queue-runner/Makefile.am
+++ b/src/hydra-queue-runner/Makefile.am
@@ -3,7 +3,8 @@ bin_PROGRAMS = hydra-queue-runner
 hydra_queue_runner_SOURCES = hydra-queue-runner.cc queue-monitor.cc dispatcher.cc \
  builder.cc build-result.cc build-remote.cc  \
  build-result.hh counter.hh pool.hh sync.hh token-server.hh state.hh db.hh \
- binary-cache-store.hh binary-cache-store.cc
+ binary-cache-store.hh binary-cache-store.cc \
+ local-binary-cache-store.hh local-binary-cache-store.cc
 hydra_queue_runner_LDADD = $(NIX_LIBS) -lpqxx
 
 AM_CXXFLAGS = $(NIX_CFLAGS) -Wall
diff --git a/src/hydra-queue-runner/binary-cache-store.cc b/src/hydra-queue-runner/binary-cache-store.cc
index 4fe11007..80720ba0 100644
--- a/src/hydra-queue-runner/binary-cache-store.cc
+++ b/src/hydra-queue-runner/binary-cache-store.cc
@@ -9,17 +9,10 @@
 
 namespace nix {
 
-BinaryCacheStore::BinaryCacheStore(ref<Store> localStore, const Path & binaryCacheDir,
+BinaryCacheStore::BinaryCacheStore(ref<Store> localStore,
     const Path & secretKeyFile, const Path & publicKeyFile)
     : localStore(localStore)
-    , binaryCacheDir(binaryCacheDir)
 {
-    createDirs(binaryCacheDir + "/nar");
-
-    Path cacheInfoFile = binaryCacheDir + "/nix-cache-info";
-    if (!pathExists(cacheInfoFile))
-        writeFile(cacheInfoFile, "StoreDir: " + settings.nixStore + "\n");
-
     if (secretKeyFile != "")
         secretKey = std::unique_ptr<SecretKey>(new SecretKey(readFile(secretKeyFile)));
 
@@ -30,27 +23,24 @@ BinaryCacheStore::BinaryCacheStore(ref<Store> localStore, const Path & binaryCac
     }
 }
 
+void BinaryCacheStore::init()
+{
+    std::string cacheInfoFile = "nix-cache-info";
+    if (!fileExists(cacheInfoFile))
+        upsertFile(cacheInfoFile, "StoreDir: " + settings.nixStore + "\n");
+}
+
 Path BinaryCacheStore::narInfoFileFor(const Path & storePath)
 {
     assertStorePath(storePath);
-    return binaryCacheDir + "/" + storePathToHash(storePath) + ".narinfo";
-}
-
-void atomicWrite(const Path & path, const std::string & s)
-{
-    Path tmp = path + ".tmp." + std::to_string(getpid());
-    AutoDelete del(tmp, false);
-    writeFile(tmp, s);
-    if (rename(tmp.c_str(), path.c_str()))
-        throw SysError(format("renaming ‘%1%’ to ‘%2%’") % tmp % path);
-    del.cancel();
+    return storePathToHash(storePath) + ".narinfo";
 }
 
 void BinaryCacheStore::addToCache(const ValidPathInfo & info,
     const string & nar)
 {
-    Path narInfoFile = narInfoFileFor(info.path);
-    if (pathExists(narInfoFile)) return;
+    auto narInfoFile = narInfoFileFor(info.path);
+    if (fileExists(narInfoFile)) return;
 
     NarInfo narInfo(info);
 
@@ -71,19 +61,18 @@ void BinaryCacheStore::addToCache(const ValidPathInfo & info,
 
     /* Atomically write the NAR file. */
     narInfo.url = "nar/" + printHash32(narInfo.fileHash) + ".nar.xz";
-    Path narFile = binaryCacheDir + "/" + narInfo.url;
-    if (!pathExists(narFile)) atomicWrite(narFile, narXz);
+    if (!fileExists(narInfo.url)) upsertFile(narInfo.url, narXz);
 
     /* Atomically write the NAR info file.*/
     if (secretKey) narInfo.sign(*secretKey);
 
-    atomicWrite(narInfoFile, narInfo.to_string());
+    upsertFile(narInfoFile, narInfo.to_string());
 }
 
 NarInfo BinaryCacheStore::readNarInfo(const Path & storePath)
 {
-    Path narInfoFile = narInfoFileFor(storePath);
-    NarInfo narInfo = NarInfo(readFile(narInfoFile), narInfoFile);
+    auto narInfoFile = narInfoFileFor(storePath);
+    auto narInfo = NarInfo(getFile(narInfoFile), narInfoFile);
     assert(narInfo.path == storePath);
 
     if (publicKeys) {
@@ -96,7 +85,7 @@ NarInfo BinaryCacheStore::readNarInfo(const Path & storePath)
 
 bool BinaryCacheStore::isValidPath(const Path & storePath)
 {
-    return pathExists(narInfoFileFor(storePath));
+    return fileExists(narInfoFileFor(storePath));
 }
 
 void BinaryCacheStore::exportPath(const Path & storePath, bool sign, Sink & sink)
@@ -105,7 +94,7 @@ void BinaryCacheStore::exportPath(const Path & storePath, bool sign, Sink & sink
 
     auto res = readNarInfo(storePath);
 
-    auto nar = readFile(binaryCacheDir + "/" + res.url);
+    auto nar = getFile(res.url);
 
     /* Decompress the NAR. FIXME: would be nice to have the remote
        side do this. */
diff --git a/src/hydra-queue-runner/binary-cache-store.hh b/src/hydra-queue-runner/binary-cache-store.hh
index ac4f2fd7..0db7ddc4 100644
--- a/src/hydra-queue-runner/binary-cache-store.hh
+++ b/src/hydra-queue-runner/binary-cache-store.hh
@@ -7,23 +7,33 @@ namespace nix {
 
 struct NarInfo;
 
-class BinaryCacheStore : public nix::Store
+class BinaryCacheStore : public Store
 {
 private:
+
     ref<Store> localStore;
-    Path binaryCacheDir;
 
     std::unique_ptr<SecretKey> secretKey;
     std::unique_ptr<PublicKeys> publicKeys;
 
+protected:
+
+    BinaryCacheStore(ref<Store> localStore,
+        const Path & secretKeyFile, const Path & publicKeyFile);
+
+    virtual bool fileExists(const std::string & path) = 0;
+
+    virtual void upsertFile(const std::string & path, const std::string & data) = 0;
+
+    virtual std::string getFile(const std::string & path) = 0;
+
 public:
 
-    BinaryCacheStore(ref<Store> localStore, const Path & binaryCacheDir,
-        const Path & secretKeyFile, const Path & publicKeyFile);
+    virtual void init();
 
 private:
 
-    Path narInfoFileFor(const Path & storePath);
+    std::string narInfoFileFor(const Path & storePath);
 
     void addToCache(const ValidPathInfo & info, const string & nar);
 
diff --git a/src/hydra-queue-runner/hydra-queue-runner.cc b/src/hydra-queue-runner/hydra-queue-runner.cc
index 9034850e..8f363ef3 100644
--- a/src/hydra-queue-runner/hydra-queue-runner.cc
+++ b/src/hydra-queue-runner/hydra-queue-runner.cc
@@ -7,7 +7,7 @@
 
 #include "state.hh"
 #include "build-result.hh"
-#include "binary-cache-store.hh"
+#include "local-binary-cache-store.hh"
 
 #include "shared.hh"
 #include "globals.hh"
@@ -33,10 +33,12 @@ ref<Store> State::getLocalStore()
 
 ref<Store> State::getDestStore()
 {
-    return make_ref<BinaryCacheStore>(getLocalStore(),
+    auto store = make_ref<LocalBinaryCacheStore>(getLocalStore(),
         "/tmp/binary-cache",
         "/home/eelco/Misc/Keys/test.nixos.org/secret",
         "/home/eelco/Misc/Keys/test.nixos.org/public");
+    store->init();
+    return store;
 }
 
 
diff --git a/src/hydra-queue-runner/local-binary-cache-store.cc b/src/hydra-queue-runner/local-binary-cache-store.cc
new file mode 100644
index 00000000..f0b2637f
--- /dev/null
+++ b/src/hydra-queue-runner/local-binary-cache-store.cc
@@ -0,0 +1,43 @@
+#include "local-binary-cache-store.hh"
+
+namespace nix {
+
+LocalBinaryCacheStore::LocalBinaryCacheStore(ref<Store> localStore,
+    const Path & binaryCacheDir,  const Path & secretKeyFile, const Path & publicKeyFile)
+    : BinaryCacheStore(localStore, secretKeyFile, publicKeyFile)
+    , binaryCacheDir(binaryCacheDir)
+{
+}
+
+void LocalBinaryCacheStore::init()
+{
+    createDirs(binaryCacheDir + "/nar");
+    BinaryCacheStore::init();
+}
+
+static void atomicWrite(const Path & path, const std::string & s)
+{
+    Path tmp = path + ".tmp." + std::to_string(getpid());
+    AutoDelete del(tmp, false);
+    writeFile(tmp, s);
+    if (rename(tmp.c_str(), path.c_str()))
+        throw SysError(format("renaming ‘%1%’ to ‘%2%’") % tmp % path);
+    del.cancel();
+}
+
+bool LocalBinaryCacheStore::fileExists(const std::string & path)
+{
+    return pathExists(binaryCacheDir + "/" + path);
+}
+
+void LocalBinaryCacheStore::upsertFile(const std::string & path, const std::string & data)
+{
+    atomicWrite(binaryCacheDir + "/" + path, data);
+}
+
+std::string LocalBinaryCacheStore::getFile(const std::string & path)
+{
+    return readFile(binaryCacheDir + "/" + path);
+}
+
+}
diff --git a/src/hydra-queue-runner/local-binary-cache-store.hh b/src/hydra-queue-runner/local-binary-cache-store.hh
new file mode 100644
index 00000000..91c56abc
--- /dev/null
+++ b/src/hydra-queue-runner/local-binary-cache-store.hh
@@ -0,0 +1,30 @@
+#pragma once
+
+#include "binary-cache-store.hh"
+
+namespace nix {
+
+class LocalBinaryCacheStore : public BinaryCacheStore
+{
+private:
+
+    Path binaryCacheDir;
+
+public:
+
+    LocalBinaryCacheStore(ref<Store> localStore, const Path & binaryCacheDir,
+        const Path & secretKeyFile, const Path & publicKeyFile);
+
+    void init() override;
+
+protected:
+
+    bool fileExists(const std::string & path) override;
+
+    void upsertFile(const std::string & path, const std::string & data) override;
+
+    std::string getFile(const std::string & path) override;
+
+};
+
+}