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 e5458f6be..ab49f70ad 100644
--- a/include/boost/geometry/algorithms/detail/buffer/buffered_piece_collection.hpp
+++ b/include/boost/geometry/algorithms/detail/buffer/buffered_piece_collection.hpp
@@ -941,8 +941,12 @@ struct buffered_piece_collection
         piece pc;
         pc.type = type;
         pc.index = static_cast<signed_size_type>(boost::size(m_pieces));
+
+        current_segment_id.piece_index = pc.index;
+
         pc.first_seg_id = current_segment_id;
 
+
         // Assign left/right (for first/last piece per ring they will be re-assigned later)
         pc.left_index = pc.index - 1;
         pc.right_index = pc.index + 1;
diff --git a/include/boost/geometry/algorithms/detail/overlay/segment_identifier.hpp b/include/boost/geometry/algorithms/detail/overlay/segment_identifier.hpp
index e77a163dd..5447c8813 100644
--- a/include/boost/geometry/algorithms/detail/overlay/segment_identifier.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/segment_identifier.hpp
@@ -38,6 +38,7 @@ struct segment_identifier
         , multi_index(-1)
         , ring_index(-1)
         , segment_index(-1)
+        , piece_index(-1)
     {}
 
     inline segment_identifier(signed_size_type src,
@@ -48,6 +49,7 @@ struct segment_identifier
         , multi_index(mul)
         , ring_index(rin)
         , segment_index(seg)
+        , piece_index(-1)
     {}
 
     inline bool operator<(segment_identifier const& other) const
@@ -85,6 +87,9 @@ struct segment_identifier
     signed_size_type multi_index;
     signed_size_type ring_index;
     signed_size_type segment_index;
+
+    // For buffer - todo: move this to buffer-only
+    signed_size_type piece_index;
 };
 
 
diff --git a/include/boost/geometry/algorithms/detail/overlay/sort_by_side.hpp b/include/boost/geometry/algorithms/detail/overlay/sort_by_side.hpp
index 78c168b5d..376f3b96e 100644
--- a/include/boost/geometry/algorithms/detail/overlay/sort_by_side.hpp
+++ b/include/boost/geometry/algorithms/detail/overlay/sort_by_side.hpp
@@ -278,7 +278,7 @@ struct side_sorter
             std::map<signed_size_type, bool> handled;
             find_open_generic
                 <
-                    &segment_identifier::multi_index
+                    &segment_identifier::piece_index
                 >(handled);
         }
         else
diff --git a/test/algorithms/buffer/buffer_linestring.cpp b/test/algorithms/buffer/buffer_linestring.cpp
index 5b0b799a6..87fed599a 100644
--- a/test/algorithms/buffer/buffer_linestring.cpp
+++ b/test/algorithms/buffer/buffer_linestring.cpp
@@ -175,10 +175,8 @@ void test_all()
     test_one<linestring, polygon>("overlapping_asym_150_100", overlapping, join_miter, end_flat, 64.984, 1.5, 1.0);
 
     // Having flat end
-#ifdef BOOST_GEOMETRY_TEST_FAIL_TANGENCIES
     test_one<linestring, polygon>("for_collinear", for_collinear, join_round, end_flat, 68.561, 2.0, 2.0);
     test_one<linestring, polygon>("for_collinear", for_collinear, join_miter, end_flat, 72, 2.0, 2.0);
-#endif
 #if defined(BOOST_GEOMETRY_BUFFER_INCLUDE_FAILING_TESTS)
     test_one<linestring, polygon>("for_collinear2", for_collinear2, join_round, end_flat, 74.387, 2.0, 2.0);
     test_one<linestring, polygon>("for_collinear2", for_collinear2, join_miter, end_flat, 78.0, 2.0, 2.0);
diff --git a/test/algorithms/buffer/buffer_multi_polygon.cpp b/test/algorithms/buffer/buffer_multi_polygon.cpp
index 09b88222a..93b748159 100644
--- a/test/algorithms/buffer/buffer_multi_polygon.cpp
+++ b/test/algorithms/buffer/buffer_multi_polygon.cpp
@@ -355,9 +355,7 @@ void test_all()
     test_one<multi_polygon_type, polygon_type>("degenerate1", degenerate1, join_round, end_flat, 5.708, 1.0);
     test_one<multi_polygon_type, polygon_type>("degenerate2", degenerate2, join_round, end_flat, 133.0166, 0.75);
 
-#ifdef BOOST_GEOMETRY_TEST_FAIL_TANGENCIES
     test_one<multi_polygon_type, polygon_type>("rt_a", rt_a, join_round, end_flat, 34.5381, 1.0);
-#endif
     test_one<multi_polygon_type, polygon_type>("rt_a", rt_a, join_miter, end_flat, 36, 1.0);
     test_one<multi_polygon_type, polygon_type>("rt_b", rt_b, join_round, end_flat, 31.4186, 1.0);
     test_one<multi_polygon_type, polygon_type>("rt_b", rt_b, join_miter, end_flat, 34, 1.0);
diff --git a/test/algorithms/buffer/buffer_polygon.cpp b/test/algorithms/buffer/buffer_polygon.cpp
index 34bfcdb77..31a91d024 100644
--- a/test/algorithms/buffer/buffer_polygon.cpp
+++ b/test/algorithms/buffer/buffer_polygon.cpp
@@ -358,9 +358,7 @@ void test_all()
     test_one<polygon_type, polygon_type>("gammagate1", gammagate, join_miter, end_flat, 88, 1);
     test_one<polygon_type, polygon_type>("fork_a1", fork_a, join_miter, end_flat, 88, 1);
     test_one<polygon_type, polygon_type>("fork_b1", fork_b, join_miter, end_flat, 154, 1);
-#ifdef BOOST_GEOMETRY_TEST_FAIL_TANGENCIES
     test_one<polygon_type, polygon_type>("fork_c1", fork_c, join_miter, end_flat, 152, 1);
-#endif
     test_one<polygon_type, polygon_type>("triangle", triangle, join_miter, end_flat, 14.6569, 1.0);
 
     test_one<polygon_type, polygon_type>("degenerate0", degenerate0, join_round, end_round, 0.0, 1.0);