diff --git a/lib/elements/dom-repeat.js b/lib/elements/dom-repeat.js
index 2983e4ba36..cd994da4b2 100644
--- a/lib/elements/dom-repeat.js
+++ b/lib/elements/dom-repeat.js
@@ -297,7 +297,7 @@ export class DomRepeat extends domRepeatBase {
     this.__sortFn = null;
     this.__filterFn = null;
     this.__observePaths = null;
-    /** @type {?function(new:TemplateInstanceBase, *)} */
+    /** @type {?function(new:TemplateInstanceBase, Object=)} */
     this.__ctor = null;
     this.__isDetached = true;
     this.template = null;
diff --git a/lib/legacy/mutable-data-behavior.js b/lib/legacy/mutable-data-behavior.js
index ee236668b7..c9f46b3a62 100644
--- a/lib/legacy/mutable-data-behavior.js
+++ b/lib/legacy/mutable-data-behavior.js
@@ -141,7 +141,6 @@ export const OptionalMutableDataBehavior = {
    * @param {*} value New property value
    * @param {*} old Previous property value
    * @return {boolean} Whether the property should be considered a change
-   * @this {this}
    * @protected
    */
   _shouldPropertyChange(property, value, old) {
diff --git a/lib/legacy/templatizer-behavior.js b/lib/legacy/templatizer-behavior.js
index 2dfbbc3a09..b06f20496f 100644
--- a/lib/legacy/templatizer-behavior.js
+++ b/lib/legacy/templatizer-behavior.js
@@ -16,7 +16,7 @@ import { TemplateInstanceBase, templatize, modelForElement } from '../utils/temp
  *   _instanceProps: Object,
  *   _forwardHostPropV2: Function,
  *   _notifyInstancePropV2: Function,
- *   ctor: TemplateInstanceBase
+ *   ctor: function(new:TemplateInstanceBase, Object=)
  * }}
  */
 let TemplatizerUser; // eslint-disable-line
@@ -99,13 +99,14 @@ export const Templatizer = {
    */
   templatize(template, mutableData) {
     this._templatizerTemplate = template;
-    this.ctor = templatize(template, this, {
-      mutableData: Boolean(mutableData),
-      parentModel: this._parentModel,
-      instanceProps: this._instanceProps,
-      forwardHostProp: this._forwardHostPropV2,
-      notifyInstanceProp: this._notifyInstancePropV2
-    });
+    this.ctor =
+        templatize(template, /** @type {!Polymer_PropertyEffects} */ (this), {
+          mutableData: Boolean(mutableData),
+          parentModel: this._parentModel,
+          instanceProps: this._instanceProps,
+          forwardHostProp: this._forwardHostPropV2,
+          notifyInstanceProp: this._notifyInstancePropV2
+        });
   },
 
   /**
diff --git a/lib/utils/templatize.js b/lib/utils/templatize.js
index ff488c15d9..9f0321f120 100644
--- a/lib/utils/templatize.js
+++ b/lib/utils/templatize.js
@@ -98,6 +98,7 @@ function upgradeTemplate(template, constructor) {
 /**
  * Base class for TemplateInstance.
  * @constructor
+ * @extends {HTMLElement}
  * @implements {Polymer_PropertyEffects}
  * @private
  */
@@ -119,7 +120,9 @@ class TemplateInstanceBase extends templateInstanceBase {
     /** @type {!StampedTemplate} */
     this.root = this._stampTemplate(this.__dataHost);
     // Save list of stamped children
-    let children = this.children = [];
+    let children = [];
+    /** @suppress {invalidCasts} */
+    this.children = /** @type {!NodeList} */ (children);
     // Polymer 1.x did not use `Polymer.dom` here so not bothering.
     for (let n = this.root.firstChild; n; n=n.nextSibling) {
       children.push(n);
@@ -532,8 +535,8 @@ function createNotifyHostPropEffect() {
  * @param {Polymer_PropertyEffects=} owner Owner of the template instances;
  *   any optional callbacks will be bound to this owner.
  * @param {Object=} options Options dictionary (see summary for details)
- * @return {function(new:TemplateInstanceBase)} Generated class bound to the template
- *   provided
+ * @return {function(new:TemplateInstanceBase, Object=)} Generated class bound
+ *   to the template provided
  * @suppress {invalidCasts}
  */
 export function templatize(template, owner, options) {