diff --git a/packages/compiler/src/render3/view/api.ts b/packages/compiler/src/render3/view/api.ts
index c12ec91acf2..5618e2e7455 100644
--- a/packages/compiler/src/render3/view/api.ts
+++ b/packages/compiler/src/render3/view/api.ts
@@ -177,7 +177,7 @@ export interface R3ComponentMetadata extends R3DirectiveMetadata {
     nodes: t.Node[];
 
     /**
-     * Any ng-content selectors extracted from the template. Contains `null` when an ng-content
+     * Any ng-content selectors extracted from the template. Contains `*` when an ng-content
      * element without selector is present.
      */
     ngContentSelectors: string[];
diff --git a/packages/compiler/src/template_parser/template_preparser.ts b/packages/compiler/src/template_parser/template_preparser.ts
index 8e9f8696814..8f10d7b6366 100644
--- a/packages/compiler/src/template_parser/template_preparser.ts
+++ b/packages/compiler/src/template_parser/template_preparser.ts
@@ -20,7 +20,7 @@ const NG_NON_BINDABLE_ATTR = 'ngNonBindable';
 const NG_PROJECT_AS = 'ngProjectAs';
 
 export function preparseElement(ast: html.Element): PreparsedElement {
-  let selectAttr: string = null!;
+  let selectAttr: string|null = null;
   let hrefAttr: string = null!;
   let relAttr: string = null!;
   let nonBindable = false;
@@ -71,7 +71,7 @@ export class PreparsedElement {
 }
 
 
-function normalizeNgContentSelect(selectAttr: string): string {
+function normalizeNgContentSelect(selectAttr: string|null): string {
   if (selectAttr === null || selectAttr.length === 0) {
     return '*';
   }