diff --git a/bin/agat b/bin/agat
index 31dc1bb7..8151ac26 100755
--- a/bin/agat
+++ b/bin/agat
@@ -194,7 +194,7 @@ force_gff_input_version, gtf_output_version, gff_output_version and output_forma
 							help        => 'Set the GTF output vesion. Choice 1, 2, 2.1, 2.2, 2.5, 3 or relax. [Default relax]',
 					 },
 					{
-							getopt      => 'deflate_attribute=s',
+							getopt      => 'deflate_attribute!',
 							help        => 'deflate multi-values attributes:  attribute_tag=att_value1,att_value2,att_value3 will will become attribute_tag=att_value1;attribute_tag2=att_value2;attribute_tag3=att_value3;',
 					 },
 					 {