diff --git a/src/internal/task/task_threads.go b/src/internal/task/task_threads.go
index 48d647f16d..2085fa979f 100644
--- a/src/internal/task/task_threads.go
+++ b/src/internal/task/task_threads.go
@@ -23,16 +23,15 @@ type state struct {
 	// is needed to be able to scan the stack.
 	stackTop uintptr
 
+	// Lowest address of the stack.
+	// This is populated when the thread is stopped by the GC.
+	stackBottom uintptr
+
 	// Next task in the activeTasks queue.
 	QueueNext *Task
 
 	// Semaphore to pause/resume the thread atomically.
 	pauseSem Semaphore
-
-	// Semaphore used for stack scanning.
-	// We can't reuse pauseSem here since the thread might have been paused for
-	// other reasons (for example, because it was waiting on a channel).
-	gcSem Semaphore
 }
 
 // Goroutine counter, starting at 0 for the main goroutine.
@@ -96,6 +95,9 @@ func (t *Task) Resume() {
 	t.state.pauseSem.Post()
 }
 
+// otherGoroutines is the total number of live goroutines minus one.
+var otherGoroutines uint32
+
 // Start a new OS thread.
 func start(fn uintptr, args unsafe.Pointer, stackSize uintptr) {
 	t := &Task{}
@@ -115,6 +117,7 @@ func start(fn uintptr, args unsafe.Pointer, stackSize uintptr) {
 	}
 	t.state.QueueNext = activeTasks
 	activeTasks = t
+	otherGoroutines++
 	activeTaskLock.Unlock()
 }
 
@@ -135,6 +138,7 @@ func taskExited(t *Task) {
 			break
 		}
 	}
+	otherGoroutines--
 	activeTaskLock.Unlock()
 
 	// Sanity check.
@@ -143,9 +147,42 @@ func taskExited(t *Task) {
 	}
 }
 
-// Futex to wait on until all tasks have finished scanning the stack.
-// This is basically a sync.WaitGroup.
-var scanDoneFutex Futex
+// scanWaitGroup is used to wait on until all threads have finished the current state transition.
+var scanWaitGroup waitGroup
+
+type waitGroup struct {
+	f Futex
+}
+
+func initWaitGroup(n uint32) waitGroup {
+	var wg waitGroup
+	wg.f.Store(n)
+	return wg
+}
+
+func (wg *waitGroup) done() {
+	if wg.f.Add(^uint32(0)) == 0 {
+		wg.f.WakeAll()
+	}
+}
+
+func (wg *waitGroup) wait() {
+	for {
+		val := wg.f.Load()
+		if val == 0 {
+			return
+		}
+		wg.f.Wait(val)
+	}
+}
+
+// gcState is used to track and notify threads when the GC is stopping/resuming.
+var gcState Futex
+
+const (
+	gcStateResumed = iota
+	gcStateStopped
+)
 
 // GC scan phase. Because we need to stop the world while scanning, this kinda
 // needs to be done in the tasks package.
@@ -155,65 +192,71 @@ var scanDoneFutex Futex
 func GCStopWorldAndScan() {
 	current := Current()
 
-	// Don't allow new goroutines to be started while pausing/resuming threads
-	// in the stop-the-world phase.
-	activeTaskLock.Lock()
+	// NOTE: This does not need to be atomic.
+	if gcState.Load() == gcStateResumed {
+		// Don't allow new goroutines to be started while pausing/resuming threads
+		// in the stop-the-world phase.
+		activeTaskLock.Lock()
 
-	// Pause all other threads.
-	numOtherThreads := uint32(0)
-	for t := activeTasks; t != nil; t = t.state.QueueNext {
-		if t != current {
-			numOtherThreads++
-			tinygo_task_send_gc_signal(t.state.thread)
-		}
-	}
+		// Wait for threads to finish resuming.
+		scanWaitGroup.wait()
 
-	// Store the number of threads to wait for in the futex.
-	// This is the equivalent of doing an initial wg.Add(numOtherThreads).
-	scanDoneFutex.Store(numOtherThreads)
+		// Change the gc state to stopped.
+		// NOTE: This does not need to be atomic.
+		gcState.Store(gcStateStopped)
 
-	// Scan the current stack, and all current registers.
-	scanCurrentStack()
+		// Set the number of threads to wait for.
+		scanWaitGroup = initWaitGroup(otherGoroutines)
 
-	// Wake each paused thread for the first time so it will scan the stack.
-	for t := activeTasks; t != nil; t = t.state.QueueNext {
-		if t != current {
-			t.state.gcSem.Post()
+		// Pause all other threads.
+		for t := activeTasks; t != nil; t = t.state.QueueNext {
+			if t != current {
+				tinygo_task_send_gc_signal(t.state.thread)
+			}
 		}
+
+		// Wait for the threads to finish stopping.
+		scanWaitGroup.wait()
 	}
 
-	// Wait until all threads have finished scanning their stack.
-	// This is the equivalent of wg.Wait()
-	for {
-		val := scanDoneFutex.Load()
-		if val == 0 {
-			break
+	// Scan other thread stacks.
+	for t := activeTasks; t != nil; t = t.state.QueueNext {
+		if t != current {
+			markRoots(t.state.stackBottom, t.state.stackTop)
 		}
-		scanDoneFutex.Wait(val)
 	}
 
+	// Scan the current stack, and all current registers.
+	scanCurrentStack()
+
 	// Scan all globals (implemented in the runtime).
 	gcScanGlobals()
 }
 
 // After the GC is done scanning, resume all other threads.
-//
-// This must only be called after a GCStopWorldAndScan call.
 func GCResumeWorld() {
-	current := Current()
-
-	// Wake each paused thread for the second time, so they will resume normal
-	// operation.
-	for t := activeTasks; t != nil; t = t.state.QueueNext {
-		if t != current {
-			t.state.gcSem.Post()
-		}
+	// NOTE: This does not need to be atomic.
+	if gcState.Load() == gcStateResumed {
+		// This is already resumed.
+		return
 	}
 
+	// Set the wait group to track resume progress.
+	scanWaitGroup = initWaitGroup(otherGoroutines)
+
+	// Set the state to resumed.
+	gcState.Store(gcStateResumed)
+
+	// Wake all of the stopped threads.
+	gcState.WakeAll()
+
 	// Allow goroutines to start and exit again.
 	activeTaskLock.Unlock()
 }
 
+//go:linkname markRoots runtime.markRoots
+func markRoots(start, end uintptr)
+
 // Scan globals, implemented in the runtime package.
 func gcScanGlobals()
 
@@ -221,34 +264,27 @@ var stackScanLock PMutex
 
 //export tinygo_task_gc_pause
 func tingyo_task_gc_pause(sig int32) {
-	// Wait until we get the signal to start scanning the stack.
-	Current().state.gcSem.Wait()
-
-	// Scan the thread stack.
-	// Only scan a single thread stack at a time, because the GC marking phase
-	// doesn't support parallelism.
-	// TODO: it may be possible to call markRoots directly (without saving
-	// registers) since we are in a signal handler that already saved a bunch of
-	// registers. This is an optimization left for a future time.
-	stackScanLock.Lock()
-	scanCurrentStack()
-	stackScanLock.Unlock()
+	// Write the entrty stack pointer to the state.
+	Current().state.stackBottom = uintptr(stacksave())
+
+	// Notify the GC that we are stopped.
+	scanWaitGroup.done()
 
-	// Equivalent of wg.Done(): subtract one from the futex and if the result is
-	// 0 (meaning we were the last in the waitgroup), wake the waiting thread.
-	n := uint32(1)
-	if scanDoneFutex.Add(-n) == 0 {
-		scanDoneFutex.Wake()
+	// Wait for the GC to resume.
+	for gcState.Load() == gcStateStopped {
+		gcState.Wait(gcStateStopped)
 	}
 
-	// Wait until we get the signal we can resume normally (after the mark phase
-	// has finished).
-	Current().state.gcSem.Wait()
+	// Notify the GC that we have resumed.
+	scanWaitGroup.done()
 }
 
 //go:export tinygo_scanCurrentStack
 func scanCurrentStack()
 
+//go:linkname stacksave runtime.stacksave
+func stacksave() unsafe.Pointer
+
 // Return the highest address of the current stack.
 func StackTop() uintptr {
 	return Current().state.stackTop
diff --git a/src/runtime/gc_boehm.go b/src/runtime/gc_boehm.go
index 08d16760c0..3b5d2ac067 100644
--- a/src/runtime/gc_boehm.go
+++ b/src/runtime/gc_boehm.go
@@ -31,10 +31,6 @@ var zeroSizedAlloc uint8
 
 var gcLock task.PMutex
 
-// Normally false, set to true during a GC scan when all other threads get
-// paused.
-var needsResumeWorld bool
-
 func initHeap() {
 	libgc_init()
 
@@ -48,20 +44,8 @@ func gcInit()
 
 //export tinygo_runtime_bdwgc_callback
 func gcCallback() {
-	if hasParallelism && needsResumeWorld {
-		// Should never happen, check for it anyway.
-		runtimePanic("gc: world already stopped")
-	}
-
 	// Mark globals and all stacks, and stop the world if we're using threading.
 	gcMarkReachable()
-
-	// If we use a scheduler with parallelism (the threads scheduler for
-	// example), we need to call gcResumeWorld() after scanning has finished.
-	if hasParallelism {
-		// Note that we need to resume the world after finishing the GC call.
-		needsResumeWorld = true
-	}
 }
 
 func markRoots(start, end uintptr) {
@@ -87,7 +71,6 @@ func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer {
 	}
 
 	gcLock.Lock()
-	needsResumeWorld = false
 	var ptr unsafe.Pointer
 	if layout == gclayout.NoPtrs.AsPtr() {
 		// This object is entirely pointer free, for example make([]int, ...).
@@ -104,9 +87,7 @@ func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer {
 		// Memory returned from libgc_malloc has already been zeroed, so nothing
 		// to do here.
 	}
-	if needsResumeWorld {
-		gcResumeWorld()
-	}
+	gcResumeWorld()
 	gcLock.Unlock()
 	if ptr == nil {
 		runtimePanic("gc: out of memory")
@@ -121,11 +102,8 @@ func free(ptr unsafe.Pointer) {
 
 func GC() {
 	gcLock.Lock()
-	needsResumeWorld = false
 	libgc_gcollect()
-	if needsResumeWorld {
-		gcResumeWorld()
-	}
+	gcResumeWorld()
 	gcLock.Unlock()
 }