diff --git a/main.nf b/main.nf
index 84bed74..fa3f798 100644
--- a/main.nf
+++ b/main.nf
@@ -109,6 +109,7 @@ process NORMALIZE_VCF {
         exit 1
     fi
 
+    tabix -p vcf input.unsorted.vcf.gz # to mitigate the header problem
     bcftools sort input.unsorted.vcf.gz -Oz -o input.vcf.gz
     tabix -p vcf input.vcf.gz
     """