diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 3252173..34d5928 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -4073,10 +4073,17 @@
 	}
 	if len(pp.timers) > 0 {
 		plocal := getg().m.p.ptr()
-		// The world is stopped so we don't need to hold timersLock.
+		// The world is stopped, but we acquire timersLock to
+		// protect against sysmon calling timeSleepUntil.
+		// This is the only case where we hold the timersLock of
+		// more than one P, so there are no deadlock concerns.
+		lock(&plocal.timersLock)
+		lock(&pp.timersLock)
 		moveTimers(plocal, pp.timers)
 		pp.timers = nil
 		pp.adjustTimers = 0
+		unlock(&pp.timersLock)
+		unlock(&plocal.timersLock)
 	}
 	// If there's a background worker, make it runnable and put
 	// it on the global queue so it can clean itself up.
diff --git a/src/runtime/time.go b/src/runtime/time.go
index 39df413..47b3262 100644
--- a/src/runtime/time.go
+++ b/src/runtime/time.go
@@ -855,8 +855,8 @@
 
 // moveTimers moves a slice of timers to pp. The slice has been taken
 // from a different P.
-// This is currently called when the world is stopped, but it could
-// work as long as the timers for pp are locked.
+// This is currently called when the world is stopped, but the caller
+// is expected to have locked the timers for pp.
 func moveTimers(pp *p, timers []*timer) {
 	for _, t := range timers {
 	loop: