diff --git a/tests/camera2/camera2_utils.h b/tests/camera2/camera2_utils.h
index ab1fcfb..a01bae2 100644
--- a/tests/camera2/camera2_utils.h
+++ b/tests/camera2/camera2_utils.h
@@ -166,7 +166,7 @@
  */
 class StreamAdapter: public camera2_stream_ops {
   public:
-    StreamAdapter(sp<IGraphicBufferProducer> consumer);
+    explicit StreamAdapter(sp<IGraphicBufferProducer> consumer);
 
     ~StreamAdapter();