diff --git a/common.wdl b/common.wdl
index 53015ace335fca2b95d294324e92c504438792bd..85ba84f392302e72bd93d06707c8ce8a202711a6 100644
--- a/common.wdl
+++ b/common.wdl
@@ -159,7 +159,7 @@ struct IndexedBamFile {
 
 struct FastqPair {
     File R1
-    String? R1_md5
+    File? R1_md5
     File? R2
-    String? R2_md5
+    File? R2_md5
 }