diff --git a/src/go/ast/commentmap.go b/src/go/ast/commentmap.go
index 2a653a60ac..5161ea70b7 100644
--- a/src/go/ast/commentmap.go
+++ b/src/go/ast/commentmap.go
@@ -315,9 +315,17 @@ loop:
 }
 
 func (cmap CommentMap) String() string {
+	// print map entries in sorted order
+	var nodes []Node
+	for node := range cmap {
+		nodes = append(nodes, node)
+	}
+	sort.Sort(byInterval(nodes))
+
 	var buf bytes.Buffer
 	fmt.Fprintln(&buf, "CommentMap {")
-	for node, comment := range cmap {
+	for _, node := range nodes {
+		comment := cmap[node]
 		// print name of identifiers; print node type for other nodes
 		var s string
 		if ident, ok := node.(*Ident); ok {