diff --git a/rpg/RapidPeptidesGenerator.py b/rpg/RapidPeptidesGenerator.py
index 378b897f004397f3fc5f194fd0c8ef6a1c7a1942..7691c6c05f2790b0e23114edbc151e576a42d243 100644
--- a/rpg/RapidPeptidesGenerator.py
+++ b/rpg/RapidPeptidesGenerator.py
@@ -255,7 +255,8 @@ def main():
                         help="Output file format. Either 'fasta', 'csv', or "
                         "'tsv' (default: fasta)")
     group_launch.add_argument("-i", "--inputdata", metavar="",
-                              help="Input file, in fasta / fastq format")
+                              help="Input file, in fasta / fastq format "\
+                                   "(gzipped or not)")
     group_launch.add_argument("-l", "--list", action="store_true",
                               help="Display the list of available enzymes")
     group_launch.add_argument("-s", "--sequence", metavar="",