diff --git a/jass_preprocessing/__main__.py b/jass_preprocessing/__main__.py
index 30d6985e955c69f27618fe80b589f39679bd1e4b..9ef13c528af2363abbdc80a24a906fd44b5d1f10 100644
--- a/jass_preprocessing/__main__.py
+++ b/jass_preprocessing/__main__.py
@@ -62,9 +62,9 @@ def launch_preprocessing(args):
         print("#SNPs mapped to reference panel: {}".format(mgwas.shape[0]))
         mgwas = jp.map_reference.compute_snp_alignement(mgwas)
         mgwas = jp.compute_score.compute_z_score(mgwas)
-        mgwas = jp.compute_score.compute_sample_size(mgwas, args.diagnostic_folder, tag, args.percent_sample_size)
+        mgwas = jp.compute_score.compute_sample_size(mgwas, args.diagnostic_folder, tag, float(args.percent_sample_size))
         end = time.time()
-        
+
         print("#SNPs remaining after sample size filter: {}".format(mgwas.shape[0]))
         print("Preprocessing of {0} in {1}s".format(tag, end-start))
         jp.save_output.save_output_by_chromosome(mgwas, args.output_folder, tag)