diff --git a/src/cmd/trace/annotations.go b/src/cmd/trace/annotations.go
index 1c0dad56d8..a276d7b642 100644
--- a/src/cmd/trace/annotations.go
+++ b/src/cmd/trace/annotations.go
@@ -370,7 +370,7 @@ func (task *taskDesc) String() string {
 	if task == nil {
 		return "task <nil>"
 	}
-	wb := new(bytes.Buffer)
+	wb := new(strings.Builder)
 	fmt.Fprintf(wb, "task %d:\t%s\n", task.id, task.name)
 	fmt.Fprintf(wb, "\tstart: %v end: %v complete: %t\n", task.firstTimestamp(), task.endTimestamp(), task.complete())
 	fmt.Fprintf(wb, "\t%d goroutines\n", len(task.goroutines))
@@ -872,7 +872,7 @@ func (h *durationHistogram) ToHTML(urlmaker func(min, max time.Duration) string)
 		}
 	}
 
-	w := new(bytes.Buffer)
+	w := new(strings.Builder)
 	fmt.Fprintf(w, `<table>`)
 	for i := h.MinBucket; i <= h.MaxBucket; i++ {
 		// Tick label.
@@ -914,7 +914,7 @@ func (h *durationHistogram) String() string {
 		}
 	}
 
-	w := new(bytes.Buffer)
+	w := new(strings.Builder)
 	for i := h.MinBucket; i <= h.MaxBucket; i++ {
 		count := h.Buckets[i]
 		bar := count * barWidth / maxCount