diff --git a/src/hydra-eval-jobs/hydra-eval-jobs.cc b/src/hydra-eval-jobs/hydra-eval-jobs.cc
index 1fe94874..237d174a 100644
--- a/src/hydra-eval-jobs/hydra-eval-jobs.cc
+++ b/src/hydra-eval-jobs/hydra-eval-jobs.cc
@@ -153,7 +153,7 @@ static void findJobsWrapped(EvalState & state, JSONObject & top,
                done. */
             if (gcRootsDir != "") {
                 Path root = gcRootsDir + "/" + baseNameOf(drvPath);
-                if (!pathExists(root)) addPermRoot(*store, drvPath, root, false);
+                if (!pathExists(root)) state.store->addPermRoot(drvPath, root, false);
             }
 
             res.attr("outputs");
@@ -253,7 +253,7 @@ int main(int argc, char * * argv)
 
         if (gcRootsDir == "") printMsg(lvlError, "warning: `--gc-roots-dir' not specified");
 
-        EvalState state(searchPath);
+        EvalState state(searchPath, openStore());
 
         AutoArgs autoArgs;
         Value * inputsSet = state.allocValue();
@@ -280,8 +280,6 @@ int main(int argc, char * * argv)
             autoArgs[sInputs].push_back(inputsSet);
         }
 
-        store = openStore();
-
         Value v;
         state.evalFile(releaseExpr, v);
 
diff --git a/src/hydra-queue-runner/build-remote.cc b/src/hydra-queue-runner/build-remote.cc
index cb6c0488..39d041d9 100644
--- a/src/hydra-queue-runner/build-remote.cc
+++ b/src/hydra-queue-runner/build-remote.cc
@@ -4,7 +4,6 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 
-#include "misc.hh"
 #include "serve-protocol.hh"
 #include "state.hh"
 #include "util.hh"
@@ -74,14 +73,14 @@ static void openConnection(Machine::ptr machine, Path tmpDir, int stderrFD, Chil
 }
 
 
-static void copyClosureTo(std::shared_ptr<StoreAPI> store,
+static void copyClosureTo(ref<Store> store,
     FdSource & from, FdSink & to, const PathSet & paths,
     counter & bytesSent,
     bool useSubstitutes = false)
 {
     PathSet closure;
     for (auto & path : paths)
-        computeFSClosure(*store, path, closure);
+        store->computeFSClosure(path, closure);
 
     /* Send the "query valid paths" command with the "lock" option
        enabled. This prevents a race where the remote host
@@ -96,7 +95,7 @@ static void copyClosureTo(std::shared_ptr<StoreAPI> store,
 
     if (present.size() == closure.size()) return;
 
-    Paths sorted = topoSortPaths(*store, closure);
+    Paths sorted = store->topoSortPaths(closure);
 
     Paths missing;
     for (auto i = sorted.rbegin(); i != sorted.rend(); ++i)
@@ -108,7 +107,7 @@ static void copyClosureTo(std::shared_ptr<StoreAPI> store,
         bytesSent += store->queryPathInfo(p).narSize;
 
     to << cmdImportPaths;
-    exportPaths(*store, missing, false, to);
+    store->exportPaths(missing, false, to);
     to.flush();
 
     if (readInt(from) != 1)
@@ -116,7 +115,7 @@ static void copyClosureTo(std::shared_ptr<StoreAPI> store,
 }
 
 
-static void copyClosureFrom(std::shared_ptr<StoreAPI> store,
+static void copyClosureFrom(ref<Store> store,
     FdSource & from, FdSink & to, const PathSet & paths, counter & bytesReceived)
 {
     to << cmdExportPaths << 0 << paths;
@@ -128,7 +127,7 @@ static void copyClosureFrom(std::shared_ptr<StoreAPI> store,
 }
 
 
-void State::buildRemote(std::shared_ptr<StoreAPI> store,
+void State::buildRemote(ref<Store> store,
     Machine::ptr machine, Step::ptr step,
     unsigned int maxSilentTime, unsigned int buildTimeout,
     RemoteResult & result)
diff --git a/src/hydra-queue-runner/build-result.cc b/src/hydra-queue-runner/build-result.cc
index 5f516d23..ebf07035 100644
--- a/src/hydra-queue-runner/build-result.cc
+++ b/src/hydra-queue-runner/build-result.cc
@@ -1,6 +1,5 @@
 #include "build-result.hh"
 #include "store-api.hh"
-#include "misc.hh"
 #include "util.hh"
 #include "regex.hh"
 
@@ -22,7 +21,7 @@ static std::tuple<bool, string> secureRead(Path fileName)
 }
 
 
-BuildOutput getBuildOutput(std::shared_ptr<StoreAPI> store, const Derivation & drv)
+BuildOutput getBuildOutput(nix::ref<Store> store, const Derivation & drv)
 {
     BuildOutput res;
 
@@ -32,7 +31,7 @@ BuildOutput getBuildOutput(std::shared_ptr<StoreAPI> store, const Derivation & d
         outputs.insert(output.second.path);
     PathSet closure;
     for (auto & output : outputs)
-        computeFSClosure(*store, output, closure);
+        store->computeFSClosure(output, closure);
     for (auto & path : closure) {
         auto info = store->queryPathInfo(path);
         res.closureSize += info.narSize;
diff --git a/src/hydra-queue-runner/build-result.hh b/src/hydra-queue-runner/build-result.hh
index e40e7dcd..7fdd659b 100644
--- a/src/hydra-queue-runner/build-result.hh
+++ b/src/hydra-queue-runner/build-result.hh
@@ -37,4 +37,4 @@ struct BuildOutput
     std::map<std::string, BuildMetric> metrics;
 };
 
-BuildOutput getBuildOutput(std::shared_ptr<nix::StoreAPI> store, const nix::Derivation & drv);
+BuildOutput getBuildOutput(nix::ref<nix::Store> store, const nix::Derivation & drv);
diff --git a/src/hydra-queue-runner/builder.cc b/src/hydra-queue-runner/builder.cc
index eef6ab50..9d1fd0dc 100644
--- a/src/hydra-queue-runner/builder.cc
+++ b/src/hydra-queue-runner/builder.cc
@@ -45,7 +45,7 @@ void State::builder(MachineReservation::ptr reservation)
 }
 
 
-bool State::doBuildStep(std::shared_ptr<StoreAPI> store, Step::ptr step,
+bool State::doBuildStep(nix::ref<Store> store, Step::ptr step,
     Machine::ptr machine)
 {
     {
@@ -354,7 +354,7 @@ bool State::doBuildStep(std::shared_ptr<StoreAPI> store, Step::ptr step,
                 /* Remember failed paths in the database so that they
                    won't be built again. */
                 if (!cachedFailure && result.status == BuildResult::PermanentFailure)
-                    for (auto & path : outputPaths(step->drv))
+                    for (auto & path : step->drv.outputPaths())
                         txn.parameterized("insert into FailedPaths values ($1)")(path).exec();
 
                 txn.commit();
diff --git a/src/hydra-queue-runner/hydra-queue-runner.cc b/src/hydra-queue-runner/hydra-queue-runner.cc
index 582a06ea..4d1146f5 100644
--- a/src/hydra-queue-runner/hydra-queue-runner.cc
+++ b/src/hydra-queue-runner/hydra-queue-runner.cc
@@ -359,7 +359,7 @@ void State::markSucceededBuild(pqxx::work & txn, Build::ptr build,
 bool State::checkCachedFailure(Step::ptr step, Connection & conn)
 {
     pqxx::work txn(conn);
-    for (auto & path : outputPaths(step->drv))
+    for (auto & path : step->drv.outputPaths())
         if (!txn.parameterized("select 1 from FailedPaths where path = $1")(path).exec().empty())
             return true;
     return false;
diff --git a/src/hydra-queue-runner/queue-monitor.cc b/src/hydra-queue-runner/queue-monitor.cc
index be8d5137..bf96f489 100644
--- a/src/hydra-queue-runner/queue-monitor.cc
+++ b/src/hydra-queue-runner/queue-monitor.cc
@@ -1,7 +1,6 @@
 #include "state.hh"
 #include "build-result.hh"
 #include "globals.hh"
-#include "misc.hh"
 
 
 using namespace nix;
@@ -64,7 +63,7 @@ void State::queueMonitorLoop()
 }
 
 
-bool State::getQueuedBuilds(Connection & conn, std::shared_ptr<StoreAPI> store, unsigned int & lastBuildId)
+bool State::getQueuedBuilds(Connection & conn, ref<Store> store, unsigned int & lastBuildId)
 {
     printMsg(lvlInfo, format("checking the queue for builds > %1%...") % lastBuildId);
 
@@ -315,7 +314,7 @@ void State::processQueueChange(Connection & conn)
 }
 
 
-Step::ptr State::createStep(std::shared_ptr<StoreAPI> store,
+Step::ptr State::createStep(ref<Store> store,
     Connection & conn, Build::ptr build, const Path & drvPath,
     Build::ptr referringBuild, Step::ptr referringStep, std::set<Path> & finishedDrvs,
     std::set<Step::ptr> & newSteps, std::set<Step::ptr> & newRunnable)
@@ -373,7 +372,7 @@ Step::ptr State::createStep(std::shared_ptr<StoreAPI> store,
        runnable while step->created == false. */
     step->drv = readDerivation(drvPath);
 
-    step->preferLocalBuild = willBuildLocally(step->drv);
+    step->preferLocalBuild = step->drv.willBuildLocally();
 
     step->systemType = step->drv.platform;
     {
@@ -391,7 +390,7 @@ Step::ptr State::createStep(std::shared_ptr<StoreAPI> store,
 
     /* Are all outputs valid? */
     bool valid = true;
-    PathSet outputs = outputPaths(step->drv);
+    PathSet outputs = step->drv.outputPaths();
     DerivationOutputs missing;
     PathSet missingPaths;
     for (auto & i : step->drv.outputs)
diff --git a/src/hydra-queue-runner/state.hh b/src/hydra-queue-runner/state.hh
index e5fd8aae..a296ddc7 100644
--- a/src/hydra-queue-runner/state.hh
+++ b/src/hydra-queue-runner/state.hh
@@ -377,12 +377,12 @@ private:
     void queueMonitorLoop();
 
     /* Check the queue for new builds. */
-    bool getQueuedBuilds(Connection & conn, std::shared_ptr<nix::StoreAPI> store, unsigned int & lastBuildId);
+    bool getQueuedBuilds(Connection & conn, nix::ref<nix::Store> store, unsigned int & lastBuildId);
 
     /* Handle cancellation, deletion and priority bumps. */
     void processQueueChange(Connection & conn);
 
-    Step::ptr createStep(std::shared_ptr<nix::StoreAPI> store,
+    Step::ptr createStep(nix::ref<nix::Store> store,
         Connection & conn, Build::ptr build, const nix::Path & drvPath,
         Build::ptr referringBuild, Step::ptr referringStep, std::set<nix::Path> & finishedDrvs,
         std::set<Step::ptr> & newSteps, std::set<Step::ptr> & newRunnable);
@@ -405,10 +405,10 @@ private:
 
     /* Perform the given build step. Return true if the step is to be
        retried. */
-    bool doBuildStep(std::shared_ptr<nix::StoreAPI> store, Step::ptr step,
+    bool doBuildStep(nix::ref<nix::Store> store, Step::ptr step,
         Machine::ptr machine);
 
-    void buildRemote(std::shared_ptr<nix::StoreAPI> store,
+    void buildRemote(nix::ref<nix::Store> store,
         Machine::ptr machine, Step::ptr step,
         unsigned int maxSilentTime, unsigned int buildTimeout,
         RemoteResult & result);