diff --git a/src/service/position-observer/position-observer-impl.js b/src/service/position-observer/position-observer-impl.js
index d3a2b846f84bf..4f526686011f8 100644
--- a/src/service/position-observer/position-observer-impl.js
+++ b/src/service/position-observer/position-observer-impl.js
@@ -206,7 +206,5 @@ export class PositionObserver {
  * @param {!../ampdoc-impl.AmpDoc} ampdoc
  */
 export function installPositionObserverServiceForDoc(ampdoc) {
-  registerServiceBuilderForDoc(ampdoc, 'position-observer', () => {
-    return new PositionObserver(ampdoc);
-  });
+  registerServiceBuilderForDoc(ampdoc, 'position-observer', PositionObserver);
 }