diff --git a/src/rmi_splitter/rmi_splitter.py b/src/rmi_splitter/rmi_splitter.py
index 095931c968e54faec72a75a053d4daa89d28a1a8..cd5ab507a406b95c7842ac75047269a8bb4b87f2 100644
--- a/src/rmi_splitter/rmi_splitter.py
+++ b/src/rmi_splitter/rmi_splitter.py
@@ -305,7 +305,7 @@ def list_reads_number(config):
         if not adaptator == 'conditions':
             if int(config[adaptator]['coords']['reads']) > read_number:
                 read_number = int(config[adaptator]['coords']['reads'])
-    return list(range(0, read_number + 1))
+    return read_number + 1
 
 
 def create_barcode_dictionaries(config, mismatch=None):
@@ -962,23 +962,17 @@ def main(argv=None):
     main function
     """
 
-    try:
-        parameters['mismatch']
-    except Exception as e:
-        parse_ntuples_fastqs(fastqs=parameters['inputfiles'],
-                             config=config,
-                             results_path=parameters['outputfolder'],
-                             verbose=parameters['verbose'],
-                             ntuple_param=parameters['ntuple'],
-                             gzed=parameters['gzed'])
+    if 'mismatch' not in parameters:
+        parameters['mismatch'] = None
     else:
-        parse_ntuples_fastqs(fastqs=parameters['inputfiles'],
-                             config=config,
-                             results_path=parameters['outputfolder'],
-                             verbose=parameters['verbose'],
-                             mismatch=int(parameters['mismatch']),
-                             ntuple_param=parameters['ntuple'],
-                             gzed=parameters['gzed'])
+        parameters['mismatch'] = int(parameters['mismatch'])
+    parse_ntuples_fastqs(fastqs=parameters['inputfiles'],
+                         config=config,
+                         results_path=parameters['outputfolder'],
+                         verbose=parameters['verbose'],
+                         mismatch=parameters['mismatch'],
+                         ntuple_param=parameters['ntuple'],
+                         gzed=parameters['gzed'])
 
 
 if __name__ == "__main__":
diff --git a/src/rmi_splitter/tests/rmi_splitter_test.py b/src/rmi_splitter/tests/rmi_splitter_test.py
index ac2d0be8653dff6eb4a91ac0c10158eb03e706b8..520e7a3246d4f79dfb48ca0248ee55cc9e299df8 100644
--- a/src/rmi_splitter/tests/rmi_splitter_test.py
+++ b/src/rmi_splitter/tests/rmi_splitter_test.py
@@ -611,7 +611,7 @@ class HandleFastqTest(unittest.TestCase):
             rmi_splitter.list_reads_number(
                 config=data_test.CONFIG_TOY_PAIRED
             ),
-            [0, 1, 2]
+            3
         )
 
     def test_assign_reads_single(self):