diff --git a/modules/mol/alg/tests/CMakeLists.txt b/modules/mol/alg/tests/CMakeLists.txt
index 09d1934f76b97f775c01381c741d1a9c33a530f5..1008a3578e384b05160bf5ea4a127d1be693b349 100644
--- a/modules/mol/alg/tests/CMakeLists.txt
+++ b/modules/mol/alg/tests/CMakeLists.txt
@@ -4,5 +4,5 @@ set(OST_MOL_ALG_UNIT_TESTS
   test_convenient_superpose.py
 )
 
-ost_unittest(mol_alg "${OST_MOL_ALG_UNIT_TESTS}")
+ost_unittest(MODULE mol_alg SOURCES "${OST_MOL_ALG_UNIT_TESTS}")
 
diff --git a/modules/mol/base/tests/CMakeLists.txt b/modules/mol/base/tests/CMakeLists.txt
index e5d1c868ca25f6b2d138e176b37ea71b806458f8..b9771e0c30ec443cba99f7cc35ee8cf6ca773a9a 100644
--- a/modules/mol/base/tests/CMakeLists.txt
+++ b/modules/mol/base/tests/CMakeLists.txt
@@ -15,7 +15,7 @@ set(OST_MOL_BASE_UNIT_TESTS
   tests.cc
 )
 
-ost_unittest(mol "${OST_MOL_BASE_UNIT_TESTS}")
+ost_unittest(MODULE mol SOURCES "${OST_MOL_BASE_UNIT_TESTS}")
 
 # for valgrind debugging
 # executable(NAME test_query_standalone SOURCES test_query_standalone.cc DEPENDS_ON mol)
diff --git a/modules/seq/alg/src/merge_pairwise_alignments.cc b/modules/seq/alg/src/merge_pairwise_alignments.cc
index 5636f32c97af7b96297663f75d6456abf954a4d4..9ebdcd142d970a9aa5c5a7b9a04969efb4f9deeb 100644
--- a/modules/seq/alg/src/merge_pairwise_alignments.cc
+++ b/modules/seq/alg/src/merge_pairwise_alignments.cc
@@ -141,9 +141,13 @@ AlignmentHandle MergePairwiseAlignments(const AlignmentList& pairwise_alns,
 
   AlignmentHandle merged=CreateAlignment();
   merged.AddSequence(shift_reference(ref_seq, shifts));
+  size_t ref_len=merged.GetSequence(0).GetLength();
   for (AlignmentList::const_iterator i=pairwise_alns.begin(),
        e=pairwise_alns.end(); i!=e; ++i) {
     SequenceHandle new_seq=realign_sequence(*i, shifts);
+    for (size_t j=new_seq.GetLength(); j<ref_len; ++j) {
+      new_seq.Append('-');
+    }
     merged.AddSequence(new_seq);
   }  
   return merged;
diff --git a/modules/seq/alg/tests/CMakeLists.txt b/modules/seq/alg/tests/CMakeLists.txt
index f6d8ebe1493d5198882f57f101956baa8e6ff830..9933524408a7fd8bcf4107c72217fe6632b7f3d3 100644
--- a/modules/seq/alg/tests/CMakeLists.txt
+++ b/modules/seq/alg/tests/CMakeLists.txt
@@ -7,5 +7,5 @@ set(OST_SEQ_ALG_UNIT_TESTS
   test_global_align.py
 )
 
-ost_unittest(seq_alg "${OST_SEQ_ALG_UNIT_TESTS}")
+ost_unittest(MODULE seq_alg SOURCES "${OST_SEQ_ALG_UNIT_TESTS}")
 
diff --git a/modules/seq/alg/tests/test_merge_pairwise_alignments.cc b/modules/seq/alg/tests/test_merge_pairwise_alignments.cc
index 3f67ac5d161840199ac352ffb09d5bf7c883603d..f89715adeccc627198420c1fc80826502db617a6 100644
--- a/modules/seq/alg/tests/test_merge_pairwise_alignments.cc
+++ b/modules/seq/alg/tests/test_merge_pairwise_alignments.cc
@@ -107,4 +107,30 @@ BOOST_AUTO_TEST_CASE(merge_pairwise_alignments_three)
   BOOST_CHECK_EQUAL(seqs[1].GetString(), "xyabcdefghijk");
   BOOST_CHECK_EQUAL(seqs[2].GetString(), "-zabcdefghijk");
 }
+
+BOOST_AUTO_TEST_CASE(merge_pairwise_alignments_four)
+{
+  SequenceHandle ref=CreateSequence("REF", "abcdefghijk");
+  SequenceHandle s1=CreateSequence("S1",   "abcdefghijk--");
+  SequenceHandle s2=CreateSequence("S2",   "abcdefghijkxy");
+  AlignmentHandle aln1=CreateAlignment();
+  aln1.AddSequence(s1);
+  aln1.AddSequence(s2);
+
+  SequenceHandle s3=CreateSequence("S1", "-abcdefghijk");
+  SequenceHandle s4=CreateSequence("S2", "zabcdefghijk");
+
+  AlignmentHandle aln2=CreateAlignment();
+  aln2.AddSequence(s3);
+  aln2.AddSequence(s4);
+  AlignmentList l;
+  l.push_back(aln1);
+  l.push_back(aln2);
+  AlignmentHandle m=alg::MergePairwiseAlignments(l, ref);
+  ConstSequenceList seqs=m.GetSequences();
+  BOOST_CHECK_EQUAL(seqs[0].GetString(), "-abcdefghijk--");
+  BOOST_CHECK_EQUAL(seqs[1].GetString(), "-abcdefghijkxy");
+  BOOST_CHECK_EQUAL(seqs[2].GetString(), "zabcdefghijk--");
+}
+
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/modules/seq/base/tests/CMakeLists.txt b/modules/seq/base/tests/CMakeLists.txt
index 528cb936ddae91eabe14d1b06c6aa743de7e29ac..645dba066e39c51c1fc0b9211228e8490ed85a07 100644
--- a/modules/seq/base/tests/CMakeLists.txt
+++ b/modules/seq/base/tests/CMakeLists.txt
@@ -7,5 +7,5 @@ set(OST_SEQ_UNIT_TESTS
   tests.cc
 )
 
-ost_unittest(seq "${OST_SEQ_UNIT_TESTS}")
+ost_unittest(MODULE seq SOURCES "${OST_SEQ_UNIT_TESTS}")