diff --git a/src/libstore/build/worker.cc b/src/libstore/build/worker.cc
index b1adf6d10..94a638725 100644
--- a/src/libstore/build/worker.cc
+++ b/src/libstore/build/worker.cc
@@ -65,7 +65,26 @@ std::pair<std::shared_ptr<G>, kj::Promise<void>> Worker::makeGoalCommon(
     auto & goal_weak = it->second;
     auto goal = goal_weak.goal.lock();
     if (!goal) {
-        goal = create();
+        struct Deleter
+        {
+            std::map<ID, CachedGoal<G>> * from;
+            std::map<ID, CachedGoal<G>>::const_iterator iter;
+
+            void operator()(G * g)
+            {
+                from->erase(iter);
+                delete g;
+            }
+        };
+
+        // this dance is necessary to be memory-safe in exceptional cases.
+        // if *anything* here throws we must still delete the goal object.
+        goal = [&] {
+            std::unique_ptr<G, Deleter> tmp(nullptr, Deleter{&map, it});
+            tmp.reset(create().release());
+            return tmp;
+        }();
+
         goal->notify = std::move(goal_weak.fulfiller);
         goal_weak.goal = goal;
         wakeUp(goal);
@@ -165,21 +184,6 @@ std::pair<GoalPtr, kj::Promise<void>> Worker::makeGoal(const DerivedPath & req,
 }
 
 
-template<typename G>
-static void removeGoal(std::shared_ptr<G> goal, auto & goalMap)
-{
-    /* !!! inefficient */
-    for (auto i = goalMap.begin();
-         i != goalMap.end(); )
-        if (i->second.goal.lock() == goal) {
-            auto j = i; ++j;
-            goalMap.erase(i);
-            i = j;
-        }
-        else ++i;
-}
-
-
 void Worker::goalFinished(GoalPtr goal, Goal::Finished & f)
 {
     goal->trace("done");
@@ -192,9 +196,16 @@ void Worker::goalFinished(GoalPtr goal, Goal::Finished & f)
     hashMismatch |= f.hashMismatch;
     checkMismatch |= f.checkMismatch;
 
-    removeGoal(goal);
     goal->notify->fulfill();
     goal->cleanup();
+
+    if (topGoals.find(goal) != topGoals.end()) {
+        topGoals.erase(goal);
+        /* If a top-level goal failed, then kill all other goals
+           (unless keepGoing was set). */
+        if (goal->exitCode == Goal::ecFailed && !settings.keepGoing)
+            topGoals.clear();
+    }
 }
 
 void Worker::handleWorkResult(GoalPtr goal, Goal::WorkResult how)
@@ -210,27 +221,6 @@ void Worker::handleWorkResult(GoalPtr goal, Goal::WorkResult how)
     updateStatistics();
 }
 
-void Worker::removeGoal(GoalPtr goal)
-{
-    if (auto drvGoal = std::dynamic_pointer_cast<DerivationGoal>(goal))
-        nix::removeGoal(drvGoal, derivationGoals);
-    else if (auto subGoal = std::dynamic_pointer_cast<PathSubstitutionGoal>(goal))
-        nix::removeGoal(subGoal, substitutionGoals);
-    else if (auto subGoal = std::dynamic_pointer_cast<DrvOutputSubstitutionGoal>(goal))
-        nix::removeGoal(subGoal, drvOutputSubstitutionGoals);
-    else
-        assert(false);
-
-    if (topGoals.find(goal) != topGoals.end()) {
-        topGoals.erase(goal);
-        /* If a top-level goal failed, then kill all other goals
-           (unless keepGoing was set). */
-        if (goal->exitCode == Goal::ecFailed && !settings.keepGoing)
-            topGoals.clear();
-    }
-}
-
-
 void Worker::wakeUp(GoalPtr goal)
 {
     goal->trace("woken up");
diff --git a/src/libstore/build/worker.hh b/src/libstore/build/worker.hh
index 1953bbec1..fb68a0ef3 100644
--- a/src/libstore/build/worker.hh
+++ b/src/libstore/build/worker.hh
@@ -158,11 +158,6 @@ private:
      */
     void waitForInput();
 
-    /**
-     * Remove a dead goal.
-     */
-    void removeGoal(GoalPtr goal);
-
     /**
      * Registers a running child process.
      */