diff --git a/libs/input/PointerController.cpp b/libs/input/PointerController.cpp
index 0a90f85..6c5f20c 100644
--- a/libs/input/PointerController.cpp
+++ b/libs/input/PointerController.cpp
@@ -39,7 +39,7 @@
     virtual ~WeakLooperCallback() { }
 
 public:
-    WeakLooperCallback(const wp<LooperCallback>& callback) :
+    explicit WeakLooperCallback(const wp<LooperCallback>& callback) :
         mCallback(callback) {
     }