diff --git a/src/internal/task/waiter.go b/src/internal/task/waiter.go
new file mode 100644
index 000000000..ac9d0d451
--- /dev/null
+++ b/src/internal/task/waiter.go
@@ -0,0 +1,99 @@
+package task
+
+import (
+	"runtime/interrupt"
+	"unsafe"
+)
+
+// A waiter waits for an interrupt to fire. Call Wait() from a goroutine to
+// pause it, and call Resume() from an interrupt handler to resume the
+// goroutine.
+type Waiter struct {
+	waiting *Task
+	lock    PMutex
+}
+
+var resumeTaskSentinel = (*Task)(unsafe.Pointer(uintptr(2)))
+var workingTaskSentinel = (*Task)(unsafe.Pointer(uintptr(1)))
+
+// Wait from a main goroutine until an interrupt calls Resume(). It will also
+// return if the interrupt called Resume() before the Wait() call (to avoid a
+// race condition).
+func (w *Waiter) Wait() {
+	if interrupt.In() {
+		runtimePanic("Waiter: called Wait from interrupt")
+	}
+
+	mask := interrupt.Disable()
+	w.lock.Lock()
+	switch w.waiting {
+	case nil, workingTaskSentinel:
+		w.waiting = Current()
+		w.lock.Unlock()
+		interrupt.Restore(mask)
+		Pause()
+	case resumeTaskSentinel:
+		// Marked as 'resume now', can return immediately.
+		w.waiting = workingTaskSentinel
+		w.lock.Unlock()
+		interrupt.Restore(mask)
+	default:
+		w.lock.Unlock()
+		interrupt.Restore(mask)
+		runtimePanic("Waiter: task is waiting already")
+	}
+}
+
+// Resume a waiting goroutine from an interrupt handler. If there is a goroutine
+// waiting, it will resume. If not, the next one that calls Wait() will
+// immediately resume.
+func (w *Waiter) Resume() {
+	if !interrupt.In() {
+		runtimePanic("Waiter: called Resume outside interrupt")
+	}
+
+	waiting := w.waiting
+	switch waiting {
+	case nil, workingTaskSentinel:
+		w.waiting = resumeTaskSentinel
+	case resumeTaskSentinel:
+		// Called Resume() twice in a row, this may indicate a bug at the caller
+		// site.
+	default:
+		// Schedule the given task to resume.
+		// If it's not yet paused, it will immediately resume on the next call
+		// to Pause().
+		w.waiting = workingTaskSentinel
+		scheduleTask(waiting)
+	}
+}
+
+// Return true if Done has not been called after a Resume call.
+// This is typically used to indicate the task outside the interrupt is still
+// being worked on.
+func (w *Waiter) Working() bool {
+	switch w.waiting {
+	case workingTaskSentinel, resumeTaskSentinel:
+		return true
+	default: // nil, <*task.Task>
+		return false
+	}
+}
+
+// Done can be called outside interrupt context to indicate the task this waiter
+// was waiting for is done, and Working() can return false. It is entirely
+// optional, if not called Working will continue to return true until it is
+// blocked in Wait() but the waiter will function normally otherwise.
+func (w *Waiter) Done() {
+	if interrupt.In() {
+		runtimePanic("Waiter: called Done from interrupt")
+	}
+
+	mask := interrupt.Disable()
+	w.lock.Lock()
+	if w.waiting == workingTaskSentinel {
+		w.waiting = nil
+	}
+	w.lock.Unlock()
+	interrupt.Restore(mask)
+}