diff --git a/src/nf_modules/macs3/main.nf b/src/nf_modules/macs3/main.nf
index 4b8aa78efc0a3a05a83dacc48eb0cd7b62de27a6..5d30355c2602846251502380a66f33ba186a9721 100644
--- a/src/nf_modules/macs3/main.nf
+++ b/src/nf_modules/macs3/main.nf
@@ -1,6 +1,8 @@
 version = "3.0.0a6"
 container_url = "lbmc/macs3:${version}"
 
+macs3_genome_size=3e9
+
 process peak_calling {
   container = "${container_url}"
   label "big_mem_multi_cpus"