diff --git a/workflow/scripts/check_design.py b/workflow/scripts/check_design.py
index a900c3b1417433b1bcad352466f8405f78f77217..083151213fe483f7cbd4a3feb76c09d760b212d7 100644
--- a/workflow/scripts/check_design.py
+++ b/workflow/scripts/check_design.py
@@ -153,7 +153,7 @@ def main():
     check_design_headers(design_df, paired)
     check_controls(design_df)
     check_replicates(design_df)
-    new_design_df = check_files(design_file, fastq_df, paired)
+    new_design_df = check_files(design_df, fastq_df, paired)
 
     # Write out new design file
     new_design_df.to_csv('design.tsv', header=True, sep='\t', index=False)