diff --git a/libs/binder/ndk/include_cpp/android/binder_auto_utils.h b/libs/binder/ndk/include_cpp/android/binder_auto_utils.h
index 439b019..18877af 100644
--- a/libs/binder/ndk/include_cpp/android/binder_auto_utils.h
+++ b/libs/binder/ndk/include_cpp/android/binder_auto_utils.h
@@ -44,9 +44,14 @@
 class SpAIBinder {
    public:
     /**
+     * Default constructor.
+     */
+    SpAIBinder() : mBinder(nullptr) {}
+
+    /**
      * Takes ownership of one strong refcount of binder.
      */
-    explicit SpAIBinder(AIBinder* binder = nullptr) : mBinder(binder) {}
+    explicit SpAIBinder(AIBinder* binder) : mBinder(binder) {}
 
     /**
      * Convenience operator for implicitly constructing an SpAIBinder from nullptr. This is not