diff --git a/pvacseq/lib/pipeline.py b/pvacseq/lib/pipeline.py
index 9662dc4..d02aef7 100644
--- a/pvacseq/lib/pipeline.py
+++ b/pvacseq/lib/pipeline.py
@@ -317,16 +317,13 @@ def generate_fasta(self, chunks):
             split_fasta_key_file_path = split_fasta_file_path + '.key'
             status_message("Generating Variant Peptide FASTA and Key Files - Entries %s" % (fasta_chunk))
             generate_fasta_params = {
-                'input_file'             : split_tsv_file_path,
-                'peptide_sequence_length': self.peptide_sequence_length,
-                'epitope_length'         : min(self.epitope_lengths),
-                'output_file'            : split_fasta_file_path,
-                'output_key_file'        : split_fasta_key_file_path,
+                'input_file'                : split_tsv_file_path,
+                'peptide_sequence_length'   : self.peptide_sequence_length,
+                'epitope_length'            : min(self.epitope_lengths),
+                'output_file'               : split_fasta_file_path,
+                'output_key_file'           : split_fasta_key_file_path,
+                'downstream_sequence_length': self.downstream_sequence_length,
             }
-            if self.downstream_sequence_length:
-                generate_fasta_params['downstream_sequence_length'] = self.downstream_sequence_length
-            else:
-                generate_fasta_params['downstream_sequence_length'] = None
             fasta_generator = FastaGenerator(**generate_fasta_params)
             fasta_generator.execute()
         status_message("Completed")
@@ -414,16 +411,13 @@ def generate_fasta(self, chunks):
             split_fasta_key_file_path = split_fasta_file_path + '.key'
             status_message("Generating Variant Peptide FASTA and Key Files - Entries %s" % (fasta_chunk))
             generate_fasta_params = {
-                'input_file'             : split_tsv_file_path,
-                'peptide_sequence_length': self.peptide_sequence_length,
-                'epitope_length'         : 9,
-                'output_file'            : split_fasta_file_path,
-                'output_key_file'        : split_fasta_key_file_path,
+                'input_file'                : split_tsv_file_path,
+                'peptide_sequence_length'   : self.peptide_sequence_length,
+                'epitope_length'            : 9,
+                'output_file'               : split_fasta_file_path,
+                'output_key_file'           : split_fasta_key_file_path,
+                'downstream_sequence_length': self.downstream_sequence_length,
             }
-            if self.downstream_sequence_length:
-                generate_fasta_params['downstream_sequence_length'] = self.downstream_sequence_length
-            else:
-                generate_fasta_params['downstream_sequence_length'] = None
             fasta_generator = FastaGenerator(**generate_fasta_params)
             fasta_generator.execute()
         status_message("Completed")