diff --git a/include/boost/unordered/detail/foa.hpp b/include/boost/unordered/detail/foa.hpp
index ee53046c..c5045685 100644
--- a/include/boost/unordered/detail/foa.hpp
+++ b/include/boost/unordered/detail/foa.hpp
@@ -1168,6 +1168,7 @@ public:
     },
     [&,this]{ /* else */
       BOOST_ASSERT(al()==x.al());
+      (void)this; /* makes sure captured this is used */
     });
     swap(size_,x.size_);
     swap(arrays,x.arrays);