diff --git a/library/core/src/main/java/com/google/android/exoplayer2/mediacodec/SynchronousMediaCodecAdapter.java b/library/core/src/main/java/com/google/android/exoplayer2/mediacodec/SynchronousMediaCodecAdapter.java
index 5995e122c0..00000fea99 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/mediacodec/SynchronousMediaCodecAdapter.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/mediacodec/SynchronousMediaCodecAdapter.java
@@ -37,7 +37,7 @@ import java.nio.ByteBuffer;
 /**
  * A {@link MediaCodecAdapter} that operates the underlying {@link MediaCodec} in synchronous mode.
  */
-public class SynchronousMediaCodecAdapter implements MediaCodecAdapter {
+public final class SynchronousMediaCodecAdapter implements MediaCodecAdapter {
 
   /** A factory for {@link SynchronousMediaCodecAdapter} instances. */
   public static class Factory implements MediaCodecAdapter.Factory {