diff --git a/include/boost/unordered/detail/foa.hpp b/include/boost/unordered/detail/foa.hpp
index 7a53c38f..f82e89c5 100644
--- a/include/boost/unordered/detail/foa.hpp
+++ b/include/boost/unordered/detail/foa.hpp
@@ -643,7 +643,7 @@ private:
         pc+=sizeof(Group);
         p+=Group::N;
       }
-      while(!(mask=reinterpret_cast<Group*>(pc)->match_occupied()));
+      while((mask=reinterpret_cast<Group*>(pc)->match_occupied())!=0);
     }
 
     auto n=unchecked_countr_zero(mask);