diff --git a/modules/gatk4/calibratedragstrmodel/meta.yml b/modules/gatk4/calibratedragstrmodel/meta.yml
index c3c40d81..e71dac5e 100644
--- a/modules/gatk4/calibratedragstrmodel/meta.yml
+++ b/modules/gatk4/calibratedragstrmodel/meta.yml
@@ -35,7 +35,7 @@ input:
       pattern: "*.{bai,crai,sai}"
   - intervals:
       type: file
-      description: BED file or interval list containing regions
+      description: BED file or interval list containing regions (optional)
       pattern: "*.{bed,interval_list}"
   - fasta:
       type: file