diff --git a/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayer.java b/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayer.java
index a9980f9803..c13fd6cacd 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayer.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayer.java
@@ -91,10 +91,9 @@ import com.google.android.exoplayer2.video.MediaCodecVideoRenderer;
  * model">
  *
  * <ul>
- *   <li>It is recommended that ExoPlayer instances are created and accessed from a single
+ *   <li>It is strongly recommended that ExoPlayer instances are created and accessed from a single
  *       application thread. The application's main thread is ideal. Accessing an instance from
- *       multiple threads is discouraged, however if an application does wish to do this then it may
- *       do so provided that it ensures accesses are synchronized.
+ *       multiple threads is discouraged as it may cause synchronization problems.
  *   <li>Registered listeners are called on the thread that created the ExoPlayer instance, unless
  *       the thread that created the ExoPlayer instance does not have a {@link Looper}. In that
  *       case, registered listeners will be called on the application's main thread.