diff --git a/media/c2/aidl/aidl_api/android.hardware.media.c2/current/android/hardware/media/c2/BaseBlock.aidl b/media/c2/aidl/aidl_api/android.hardware.media.c2/current/android/hardware/media/c2/BaseBlock.aidl
index 460ff97522..069b2cf244 100644
--- a/media/c2/aidl/aidl_api/android.hardware.media.c2/current/android/hardware/media/c2/BaseBlock.aidl
+++ b/media/c2/aidl/aidl_api/android.hardware.media.c2/current/android/hardware/media/c2/BaseBlock.aidl
@@ -35,5 +35,6 @@ package android.hardware.media.c2;
 @VintfStability
 union BaseBlock {
   android.hardware.common.NativeHandle nativeBlock;
+  android.hardware.HardwareBuffer hwbBlock;
   android.hardware.media.bufferpool2.BufferStatusMessage pooledBlock;
 }
diff --git a/media/c2/aidl/android/hardware/media/c2/BaseBlock.aidl b/media/c2/aidl/android/hardware/media/c2/BaseBlock.aidl
index 8b8b8e0e46..7cc041c1ce 100644
--- a/media/c2/aidl/android/hardware/media/c2/BaseBlock.aidl
+++ b/media/c2/aidl/android/hardware/media/c2/BaseBlock.aidl
@@ -16,6 +16,7 @@
 
 package android.hardware.media.c2;
 
+import android.hardware.HardwareBuffer;
 import android.hardware.common.NativeHandle;
 
 /**
@@ -31,6 +32,10 @@ union BaseBlock {
      * #nativeBlock is the opaque representation of a buffer.
      */
     NativeHandle nativeBlock;
+    /**
+     * #hwbBlock is the opaque representation of a GraphicBuffer
+     */
+    HardwareBuffer hwbBlock;
     /**
      * #pooledBlock is a reference to a buffer handled by a BufferPool.
      */