diff --git a/dom/animation/AnimationPlayer.cpp b/dom/animation/AnimationPlayer.cpp
index c6f4775e4343..769a9588ff2b 100644
--- a/dom/animation/AnimationPlayer.cpp
+++ b/dom/animation/AnimationPlayer.cpp
@@ -70,6 +70,7 @@ AnimationPlayer::SetStartTime(const Nullable<TimeDuration>& aNewStartTime)
   }
 
   UpdateSourceContent();
+  PostUpdate();
 
   // FIXME: Once bug 1074630 is fixed, run the procedure to update a player's
   // finished state for player: