diff --git a/src/unique_ptr.rs b/src/unique_ptr.rs
index ca527d2..c8c5a67 100644
--- a/src/unique_ptr.rs
+++ b/src/unique_ptr.rs
@@ -122,6 +122,8 @@
 // codebase.
 pub unsafe trait UniquePtrTarget {
     #[doc(hidden)]
+    const __NAME: &'static str;
+    #[doc(hidden)]
     fn __null() -> *mut c_void;
     #[doc(hidden)]
     fn __new(value: Self) -> *mut c_void
@@ -157,6 +159,7 @@
 }
 
 unsafe impl UniquePtrTarget for CxxString {
+    const __NAME: &'static str = "CxxString";
     fn __null() -> *mut c_void {
         let mut repr = ptr::null_mut::<c_void>();
         unsafe { unique_ptr_std_string_null(&mut repr) }