diff --git a/base/include/hidl/HidlSupport.h b/base/include/hidl/HidlSupport.h
index 55f21ea..98b37ab 100644
--- a/base/include/hidl/HidlSupport.h
+++ b/base/include/hidl/HidlSupport.h
@@ -334,7 +334,7 @@
     }
 
     // Note, does not initialize primitive types.
-    hidl_vec(size_t size) : hidl_vec() { resize(size); }
+    explicit hidl_vec(size_t size) : hidl_vec() { resize(size); }
 
     hidl_vec(const hidl_vec<T> &other) : hidl_vec() {
         *this = other;