diff --git a/include/gui/BufferQueue.h b/include/gui/BufferQueue.h
index 09300a2..a23ed57 100644
--- a/include/gui/BufferQueue.h
+++ b/include/gui/BufferQueue.h
@@ -60,7 +60,7 @@
     // weak references.
     class ProxyConsumerListener : public BnConsumerListener {
     public:
-        ProxyConsumerListener(const wp<ConsumerListener>& consumerListener);
+        explicit ProxyConsumerListener(const wp<ConsumerListener>& consumerListener);
         virtual ~ProxyConsumerListener();
         virtual void onFrameAvailable(const BufferItem& item) override;
         virtual void onFrameReplaced(const BufferItem& item) override;