diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index d96a4dc68ab..664e2d0319d 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -520,7 +520,6 @@ namespace ts {
         result += diag.messageText;
         indent++;
         if (diag.next) {
-            // TODO: Should be possible to optimise the common, non-tree case
             for (const kid of diag.next) {
                 result += flattenDiagnosticMessageText(kid, newLine, indent);
             }