diff --git a/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp b/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
index b57d27ed4..805f3923e 100644
--- a/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/copy_segments.hpp
@@ -89,7 +89,7 @@ struct copy_segments_ring
         typedef typename boost::range_difference<Ring>::type size_type;
         size_type const count = from_index <= to_index
             ? to_index - from_index + 1
-            : boost::size(view) - from_index + to_index + 1;
+            : int(boost::size(view)) - from_index + to_index + 1;
 
         for (size_type i = 0; i < count; ++i, ++it)
         {
@@ -117,7 +117,7 @@ struct copy_segments_linestring
         int const from_index = seg_id.segment_index + 1;
 
         // Sanity check
-        if (from_index > to_index || from_index < 0 || to_index >= boost::size(ls))
+        if (from_index > to_index || from_index < 0 || to_index >= int(boost::size(ls)))
         {
             return;
         }
diff --git a/include/boost/geometry/multi/algorithms/detail/overlay/copy_segment_point.hpp b/include/boost/geometry/multi/algorithms/detail/overlay/copy_segment_point.hpp
index 1093a8456..72be5ddbf 100644
--- a/include/boost/geometry/multi/algorithms/detail/overlay/copy_segment_point.hpp
+++ b/include/boost/geometry/multi/algorithms/detail/overlay/copy_segment_point.hpp
@@ -42,7 +42,7 @@ struct copy_segment_point_multi
         BOOST_ASSERT
             (
                 seg_id.multi_index >= 0
-                && seg_id.multi_index < boost::size(multi)
+                && seg_id.multi_index < int(boost::size(multi))
             );
 
         // Call the single-version
diff --git a/include/boost/geometry/multi/algorithms/detail/overlay/copy_segments.hpp b/include/boost/geometry/multi/algorithms/detail/overlay/copy_segments.hpp
index a234e240d..f474b12fd 100644
--- a/include/boost/geometry/multi/algorithms/detail/overlay/copy_segments.hpp
+++ b/include/boost/geometry/multi/algorithms/detail/overlay/copy_segments.hpp
@@ -44,7 +44,7 @@ struct copy_segments_multi
         BOOST_ASSERT
             (
                 seg_id.multi_index >= 0
-                && seg_id.multi_index < boost::size(multi_geometry)
+                && seg_id.multi_index < int(boost::size(multi_geometry))
             );
 
         // Call the single-version
diff --git a/include/boost/geometry/multi/algorithms/detail/overlay/get_ring.hpp b/include/boost/geometry/multi/algorithms/detail/overlay/get_ring.hpp
index 8cdd7ed97..e23acf99b 100644
--- a/include/boost/geometry/multi/algorithms/detail/overlay/get_ring.hpp
+++ b/include/boost/geometry/multi/algorithms/detail/overlay/get_ring.hpp
@@ -35,7 +35,7 @@ struct get_ring<multi_polygon_tag>
         BOOST_ASSERT
             (
                 id.multi_index >= 0
-                && id.multi_index < boost::size(multi_polygon)
+                && id.multi_index < int(boost::size(multi_polygon))
             );
         return get_ring<polygon_tag>::apply(id,
                     multi_polygon[id.multi_index]);
diff --git a/include/boost/geometry/multi/algorithms/detail/sections/range_by_section.hpp b/include/boost/geometry/multi/algorithms/detail/sections/range_by_section.hpp
index cf4bf5d83..28a4805ed 100644
--- a/include/boost/geometry/multi/algorithms/detail/sections/range_by_section.hpp
+++ b/include/boost/geometry/multi/algorithms/detail/sections/range_by_section.hpp
@@ -46,7 +46,7 @@ struct full_section_multi
         BOOST_ASSERT
             (
                 section.ring_id.multi_index >= 0
-                && section.ring_id.multi_index < boost::size(multi)
+                && section.ring_id.multi_index < int(boost::size(multi))
             );
 
         return Policy::apply(multi[section.ring_id.multi_index], section);