diff --git a/doc/changes.qbk b/doc/changes.qbk
index d1b26254..790e3863 100644
--- a/doc/changes.qbk
+++ b/doc/changes.qbk
@@ -107,5 +107,7 @@ First official release.
 
 * Support instantiating the containers with incomplete value types.
 * Reduced the number of warnings (mostly in tests).
+* [@http://svn.boost.org/trac/boost/ticket/3773 Ticket 3773]:
+  Add missing `std` qualifier to `ptrdiff_t`.
 
 [endsect]
diff --git a/include/boost/unordered/detail/buckets.hpp b/include/boost/unordered/detail/buckets.hpp
index c4b8a898..b1dee5cf 100644
--- a/include/boost/unordered/detail/buckets.hpp
+++ b/include/boost/unordered/detail/buckets.hpp
@@ -148,7 +148,7 @@ namespace boost { namespace unordered_detail {
 
         // Set up the sentinel (node_ptr cast)
         bucket_ptr sentinel = constructor.get() +
-            static_cast<ptrdiff_t>(this->bucket_count_);
+            static_cast<std::ptrdiff_t>(this->bucket_count_);
         sentinel->next_ = sentinel;
 
         // Only release the buckets once everything is successfully