diff --git a/library/core/src/main/java/com/google/android/exoplayer2/upstream/BandwidthMeter.java b/library/core/src/main/java/com/google/android/exoplayer2/upstream/BandwidthMeter.java
index 31e034d9d1..73e9225b41 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/upstream/BandwidthMeter.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/upstream/BandwidthMeter.java
@@ -47,5 +47,6 @@ public interface BandwidthMeter {
    * Returns the {@link TransferListener} that this instance uses to gather bandwidth information
    * from data transfers. May be null, if no transfer listener is used.
    */
-  @Nullable TransferListener<?> getTransferListener();
+  @Nullable
+  TransferListener<? super DataSource> getTransferListener();
 }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/upstream/DefaultBandwidthMeter.java b/library/core/src/main/java/com/google/android/exoplayer2/upstream/DefaultBandwidthMeter.java
index b1bc2c17d2..080165164d 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/upstream/DefaultBandwidthMeter.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/upstream/DefaultBandwidthMeter.java
@@ -172,7 +172,7 @@ public final class DefaultBandwidthMeter implements BandwidthMeter, TransferList
   }
 
   @Override
-  public @Nullable TransferListener<?> getTransferListener() {
+  public @Nullable TransferListener<? super DataSource> getTransferListener() {
     return this;
   }