diff --git a/src/runtime/time.go b/src/runtime/time.go
index 31c83ca4e3..06a56bf7ae 100644
--- a/src/runtime/time.go
+++ b/src/runtime/time.go
@@ -778,6 +778,11 @@ func (ts *timers) adjust(now int64, force bool) {
 			throw("bad ts")
 		}
 
+		if t.astate.Load()&(timerModified|timerZombie) == 0 {
+			// Does not need adjustment.
+			continue
+		}
+
 		t.lock()
 		if t.state&timerHeaped == 0 {
 			badTimer()
diff --git a/src/time/sleep_test.go b/src/time/sleep_test.go
index 634a5c7a13..29f56ef752 100644
--- a/src/time/sleep_test.go
+++ b/src/time/sleep_test.go
@@ -971,3 +971,21 @@ func doWork(dur Duration) {
 	for Since(start) < dur {
 	}
 }
+
+func BenchmarkAdjustTimers10000(b *testing.B) {
+	benchmark(b, func(pb *testing.PB) {
+		for pb.Next() {
+			const n = 10000
+			timers := make([]*Timer, 0, n)
+			for range n {
+				t := AfterFunc(Hour, func() {})
+				timers = append(timers, t)
+			}
+			timers[n-1].Reset(Nanosecond)
+			Sleep(Microsecond)
+			for _, t := range timers {
+				t.Stop()
+			}
+		}
+	})
+}