diff --git a/common.wdl b/common.wdl
index 15e99f5804089fdd328f263b21804dc18712e752..379da32aa5d4b795960918ce488811e4a16013ce 100644
--- a/common.wdl
+++ b/common.wdl
@@ -134,3 +134,9 @@ task StringArrayMd5 {
         memory: 1
     }
 }
+
+struct Reference {
+    File fasta
+    File fai
+    File dict
+}