diff --git a/src/hydra-queue-runner/hydra-queue-runner.cc b/src/hydra-queue-runner/hydra-queue-runner.cc
index 7656d8ea..1e7ff7cc 100644
--- a/src/hydra-queue-runner/hydra-queue-runner.cc
+++ b/src/hydra-queue-runner/hydra-queue-runner.cc
@@ -21,10 +21,6 @@ State::State()
     if (hydraData == "") throw Error("$HYDRA_DATA must be set");
 
     logDir = canonPath(hydraData + "/build-logs");
-
-    localPlatforms = {settings.thisSystem};
-    if (settings.thisSystem == "x86_64-linux")
-        localPlatforms.insert("i686-linux");
 }
 
 
@@ -97,7 +93,7 @@ void State::monitorMachinesFile()
         getEnv("NIX_REMOTE_SYSTEMS", pathExists(defaultMachinesFile) ? defaultMachinesFile : ""), ":");
 
     if (machinesFiles.empty()) {
-        parseMachines("localhost " + concatStringsSep(",", localPlatforms)
+        parseMachines("localhost " + settings.thisSystem
             + " - " + int2String(settings.maxBuildJobs) + " 1");
         return;
     }
diff --git a/src/hydra-queue-runner/queue-monitor.cc b/src/hydra-queue-runner/queue-monitor.cc
index da250f5a..0694facc 100644
--- a/src/hydra-queue-runner/queue-monitor.cc
+++ b/src/hydra-queue-runner/queue-monitor.cc
@@ -1,6 +1,7 @@
 #include "state.hh"
 #include "build-result.hh"
 #include "globals.hh"
+#include "misc.hh"
 
 
 using namespace nix;
@@ -358,10 +359,7 @@ Step::ptr State::createStep(std::shared_ptr<StoreAPI> store,
        runnable while step->created == false. */
     step->drv = readDerivation(drvPath);
 
-    auto attr = step->drv.env.find("preferLocalBuild");
-    step->preferLocalBuild =
-        attr != step->drv.env.end() && attr->second == "1"
-        && has(localPlatforms, step->drv.platform);
+    step->preferLocalBuild = willBuildLocally(step->drv);
 
     step->systemType = step->drv.platform;
     {
diff --git a/src/hydra-queue-runner/state.hh b/src/hydra-queue-runner/state.hh
index 838338aa..fda04192 100644
--- a/src/hydra-queue-runner/state.hh
+++ b/src/hydra-queue-runner/state.hh
@@ -259,8 +259,6 @@ private:
 
     nix::Path hydraData, logDir;
 
-    nix::StringSet localPlatforms;
-
     /* The queued builds. */
     typedef std::map<BuildID, Build::ptr> Builds;
     Sync<Builds> builds;