diff --git a/modules/seq/base/tests/test_aligned_region.cc b/modules/seq/base/tests/test_aligned_region.cc
index 93acaf4aa7c4f0034130aa4aab25264dfb2a8956..249da58065d52c544774c8cf8b3dbe4c4bbbf3e6 100644
--- a/modules/seq/base/tests/test_aligned_region.cc
+++ b/modules/seq/base/tests/test_aligned_region.cc
@@ -105,18 +105,47 @@ BOOST_AUTO_TEST_CASE(aligned_region_replace)
   a1.AddSequence(seq11);
   a1.AddSequence(seq12);
   AlignedRegion ar1 = a1.MakeRegion(1,2);
-
   AlignmentHandle a2 = CreateAlignment();
   SequenceHandle seq21 = CreateSequence("S1","zzzzzzz");
   SequenceHandle seq22 = CreateSequence("S2","ee-----");
   a2.AddSequence(seq21);
   a2.AddSequence(seq22);
   AlignedRegion ar2 = a2.MakeRegion(1,2);
-
   ar1.Replace(ar2);
   BOOST_CHECK_EQUAL(a1.GetSequence(0).GetString(),"azzcdef");
   BOOST_CHECK_EQUAL(a1.GetSequence(1).GetString(),"ge-jk-l");
 
+  a1 = CreateAlignment();
+  seq11 = CreateSequence("S1","ab-cdef");
+  seq12 = CreateSequence("S2","ghijk-l");
+  a1.AddSequence(seq11);
+  a1.AddSequence(seq12);
+  ar1 = a1.MakeRegion(1,2);
+  a2 = CreateAlignment();
+  seq21 = CreateSequence("S1","zzzzzzz");
+  seq22 = CreateSequence("S2","ee-----");
+  a2.AddSequence(seq21);
+  a2.AddSequence(seq22);
+  ar2 = a2.MakeRegion(1,0);
+  ar1.Replace(ar2);
+  BOOST_CHECK_EQUAL(a1.GetSequence(0).GetString(),"acdef");
+  BOOST_CHECK_EQUAL(a1.GetSequence(1).GetString(),"gjk-l");
+
+  a1 = CreateAlignment();
+  seq11 = CreateSequence("S1","ab-cdef");
+  seq12 = CreateSequence("S2","ghijk-l");
+  a1.AddSequence(seq11);
+  a1.AddSequence(seq12);
+  ar1 = a1.MakeRegion(1,2);
+  a2 = CreateAlignment();
+  seq21 = CreateSequence("S1","zzzzzzz");
+  seq22 = CreateSequence("S2","ee-----");
+  a2.AddSequence(seq21);
+  a2.AddSequence(seq22);
+  ar2 = a2.MakeRegion(1,3);
+  ar1.Replace(ar2);
+  BOOST_CHECK_EQUAL(a1.GetSequence(0).GetString(),"azzzcdef");
+  BOOST_CHECK_EQUAL(a1.GetSequence(1).GetString(),"ge--jk-l");
 }
 
 BOOST_AUTO_TEST_CASE(aligned_region_shift)