diff --git a/core/tests/test_pm3argparse.py b/core/tests/test_pm3argparse.py
index 878008b5ffa97b15acc81dd7e18cdc62673b1e3a..33df7af8cbbed77b0c25218b6d2d818423cd39d1 100644
--- a/core/tests/test_pm3argparse.py
+++ b/core/tests/test_pm3argparse.py
@@ -1242,7 +1242,7 @@ class PM3ArgParseTests(unittest.TestCase):
         parser.AssembleParser()
         opts =  parser.Parse(['-f', 'data/aln_tpl/1crn.fasta',
                               '-f', 'data/aln_tpl/5ua4_B.fasta',
-                              '--use_fragments'])
+                              '--use-fragments'])
         self.assertEqual(len(opts.alignments), 2)
         self.assertEqual(len(opts.fragger_handles), 2)
         self.assertEqual(opts.alignments[0].GetSequence(0).GetGaplessString(),
@@ -1271,7 +1271,7 @@ class PM3ArgParseTests(unittest.TestCase):
                               '-f', 'data/aln_tpl/5ua4_B.fasta',
                               '-s', 'data/aln_tpl/1crn.hhm',
                               '-s', 'data/aln_tpl/5ua4_B.hhm',
-                              '--use_fragments'])
+                              '--use-fragments'])
         self.assertEqual(len(opts.alignments), 2)
         self.assertEqual(len(opts.fragger_handles), 2)
         self.assertEqual(opts.alignments[0].GetSequence(0).GetGaplessString(),