diff --git a/src/libstore/build/local-derivation-goal.hh b/src/libstore/build/local-derivation-goal.hh
index 6239129ab..52b7d4c2e 100644
--- a/src/libstore/build/local-derivation-goal.hh
+++ b/src/libstore/build/local-derivation-goal.hh
@@ -182,7 +182,7 @@ struct LocalDerivationGoal : public DerivationGoal
      * Create a LocalDerivationGoal without an on-disk .drv file,
      * possibly a platform-specific subclass
      */
-    static std::shared_ptr<LocalDerivationGoal> makeLocalDerivationGoal(
+    static std::unique_ptr<LocalDerivationGoal> makeLocalDerivationGoal(
         const StorePath & drvPath,
         const OutputsSpec & wantedOutputs,
         Worker & worker,
@@ -194,7 +194,7 @@ struct LocalDerivationGoal : public DerivationGoal
      * Create a LocalDerivationGoal for an on-disk .drv file,
      * possibly a platform-specific subclass
      */
-    static std::shared_ptr<LocalDerivationGoal> makeLocalDerivationGoal(
+    static std::unique_ptr<LocalDerivationGoal> makeLocalDerivationGoal(
         const StorePath & drvPath,
         const BasicDerivation & drv,
         const OutputsSpec & wantedOutputs,
diff --git a/src/libstore/build/worker.cc b/src/libstore/build/worker.cc
index 68071a94c..18cdde63a 100644
--- a/src/libstore/build/worker.cc
+++ b/src/libstore/build/worker.cc
@@ -55,7 +55,7 @@ Worker::~Worker()
 std::pair<std::shared_ptr<DerivationGoal>, kj::Promise<void>> Worker::makeDerivationGoalCommon(
     const StorePath & drvPath,
     const OutputsSpec & wantedOutputs,
-    std::function<std::shared_ptr<DerivationGoal>()> mkDrvGoal)
+    std::function<std::unique_ptr<DerivationGoal>()> mkDrvGoal)
 {
     auto & goal_weak = derivationGoals[drvPath];
     std::shared_ptr<DerivationGoal> goal = goal_weak.goal.lock();
@@ -78,9 +78,9 @@ std::pair<std::shared_ptr<DerivationGoal>, kj::Promise<void>> Worker::makeDeriva
     return makeDerivationGoalCommon(
         drvPath,
         wantedOutputs,
-        [&]() -> std::shared_ptr<DerivationGoal> {
+        [&]() -> std::unique_ptr<DerivationGoal> {
             return !dynamic_cast<LocalStore *>(&store)
-                ? std::make_shared<DerivationGoal>(
+                ? std::make_unique<DerivationGoal>(
                     drvPath, wantedOutputs, *this, running, buildMode
                 )
                 : LocalDerivationGoal::makeLocalDerivationGoal(
@@ -101,9 +101,9 @@ std::pair<std::shared_ptr<DerivationGoal>, kj::Promise<void>> Worker::makeBasicD
     return makeDerivationGoalCommon(
         drvPath,
         wantedOutputs,
-        [&]() -> std::shared_ptr<DerivationGoal> {
+        [&]() -> std::unique_ptr<DerivationGoal> {
             return !dynamic_cast<LocalStore *>(&store)
-                ? std::make_shared<DerivationGoal>(
+                ? std::make_unique<DerivationGoal>(
                     drvPath, drv, wantedOutputs, *this, running, buildMode
                 )
                 : LocalDerivationGoal::makeLocalDerivationGoal(
diff --git a/src/libstore/build/worker.hh b/src/libstore/build/worker.hh
index 925d289bf..46adaa145 100644
--- a/src/libstore/build/worker.hh
+++ b/src/libstore/build/worker.hh
@@ -245,7 +245,7 @@ public:
 private:
     std::pair<std::shared_ptr<DerivationGoal>, kj::Promise<void>> makeDerivationGoalCommon(
         const StorePath & drvPath, const OutputsSpec & wantedOutputs,
-        std::function<std::shared_ptr<DerivationGoal>()> mkDrvGoal);
+        std::function<std::unique_ptr<DerivationGoal>()> mkDrvGoal);
     std::pair<std::shared_ptr<DerivationGoal>, kj::Promise<void>> makeDerivationGoal(
         const StorePath & drvPath,
         const OutputsSpec & wantedOutputs, BuildMode buildMode = bmNormal) override;
diff --git a/src/libstore/platform.cc b/src/libstore/platform.cc
index f2c023c82..36f8e352a 100644
--- a/src/libstore/platform.cc
+++ b/src/libstore/platform.cc
@@ -25,7 +25,7 @@ std::shared_ptr<LocalStore> LocalStore::makeLocalStore(const Params & params)
 #endif
 }
 
-std::shared_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoal(
+std::unique_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoal(
     const StorePath & drvPath,
     const OutputsSpec & wantedOutputs,
     Worker & worker,
@@ -34,17 +34,17 @@ std::shared_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoa
 )
 {
 #if __linux__
-    return std::make_shared<LinuxLocalDerivationGoal>(drvPath, wantedOutputs, worker, isDependency, buildMode);
+    return std::make_unique<LinuxLocalDerivationGoal>(drvPath, wantedOutputs, worker, isDependency, buildMode);
 #elif __APPLE__
-    return std::make_shared<DarwinLocalDerivationGoal>(drvPath, wantedOutputs, worker, isDependency, buildMode);
+    return std::make_unique<DarwinLocalDerivationGoal>(drvPath, wantedOutputs, worker, isDependency, buildMode);
 #elif __FreeBSD__
-    return std::make_shared<FreeBSDLocalDerivationGoal>(drvPath, wantedOutputs, worker, isDependency, buildMode);
+    return std::make_unique<FreeBSDLocalDerivationGoal>(drvPath, wantedOutputs, worker, isDependency, buildMode);
 #else
-    return std::make_shared<FallbackLocalDerivationGoal>(drvPath, wantedOutputs, worker, isDependency, buildMode);
+    return std::make_unique<FallbackLocalDerivationGoal>(drvPath, wantedOutputs, worker, isDependency, buildMode);
 #endif
 }
 
-std::shared_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoal(
+std::unique_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoal(
     const StorePath & drvPath,
     const BasicDerivation & drv,
     const OutputsSpec & wantedOutputs,
@@ -54,19 +54,19 @@ std::shared_ptr<LocalDerivationGoal> LocalDerivationGoal::makeLocalDerivationGoa
 )
 {
 #if __linux__
-    return std::make_shared<LinuxLocalDerivationGoal>(
+    return std::make_unique<LinuxLocalDerivationGoal>(
         drvPath, drv, wantedOutputs, worker, isDependency, buildMode
     );
 #elif __APPLE__
-    return std::make_shared<DarwinLocalDerivationGoal>(
+    return std::make_unique<DarwinLocalDerivationGoal>(
         drvPath, drv, wantedOutputs, worker, isDependency, buildMode
     );
 #elif __FreeBSD__
-    return std::make_shared<FreeBSDLocalDerivationGoal>(
+    return std::make_unique<FreeBSDLocalDerivationGoal>(
         drvPath, drv, wantedOutputs, worker, isDependency, buildMode
     );
 #else
-    return std::make_shared<FallbackLocalDerivationGoal>(
+    return std::make_unique<FallbackLocalDerivationGoal>(
         drvPath, drv, wantedOutputs, worker, isDependency, buildMode
     );
 #endif