diff --git a/include/boost/geometry/algorithms/detail/buffer/buffered_piece_collection.hpp b/include/boost/geometry/algorithms/detail/buffer/buffered_piece_collection.hpp
index 5e7da79ec..46a7c0f7a 100644
--- a/include/boost/geometry/algorithms/detail/buffer/buffered_piece_collection.hpp
+++ b/include/boost/geometry/algorithms/detail/buffer/buffered_piece_collection.hpp
@@ -844,7 +844,7 @@ struct buffered_piece_collection
             return;
         }
 
-        if (m_first_piece_index < static_cast<int>(boost::size(m_pieces)))
+        if (m_first_piece_index < static_cast<signed_size_type>(boost::size(m_pieces)))
         {
             // If piece was added
             // Reassign left-of-first and right-of-last