diff --git a/src/runtime.js b/src/runtime.js
index d050a891191e..81a105aa71ac 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -514,6 +514,8 @@ function registerElementClass(global, name, implementationClass, opt_css) {
  */
 function prepareAndRegisterServiceForDoc(global, extensions,
     name, opt_ctor, opt_factory) {
+  // TODO(kmh287, #9292): Refactor to remove opt_factory param and require ctor
+  // once #9212 has been in prod for two releases.
   const ampdocService = ampdocServiceFor(global);
   const ampdoc = ampdocService.getAmpDoc();
   registerServiceForDoc(ampdoc, name, opt_ctor, opt_factory);
@@ -530,6 +532,8 @@ function prepareAndRegisterServiceForDoc(global, extensions,
  */
 function prepareAndRegisterServiceForDocShadowMode(global, extensions,
     name, opt_ctor, opt_factory) {
+  // TODO(kmh287, #9292): Refactor to remove opt_factory param and require ctor
+  // once #9212 has been in prod for two releases.
   addDocFactoryToExtension(extensions, ampdoc => {
     registerServiceForDoc(ampdoc, name, opt_ctor, opt_factory);
   }, name);
@@ -545,8 +549,8 @@ function prepareAndRegisterServiceForDocShadowMode(global, extensions,
  * @param {function(!./service/ampdoc-impl.AmpDoc):!Object=} opt_factory
  */
 function registerServiceForDoc(ampdoc, name, opt_ctor, opt_factory) {
-  // TODO(kmh287, #9292): Refactor to remove opt_factory param once #9212 has been
-  // in prod for two releases.
+  // TODO(kmh287, #9292): Refactor to remove opt_factory param and require ctor
+  // once #9212 has been in prod for two releases.
   // Wrapping factory in function is necessary as opt_factory could be an
   // arrow function, which cannot be used as constructors.
   const ctor = opt_ctor || function(ampdoc) {