diff --git a/macs2.wdl b/macs2.wdl
index 70fea707d138cda234a087e39550cef09f757654..2c3bf57ce5671c984634420258e055248f0df16d 100644
--- a/macs2.wdl
+++ b/macs2.wdl
@@ -34,7 +34,7 @@ task PeakCalling {
         Int? extsize
         Int? shiftsize
         Float? pval_thres
-        Boolean? bdg
+        Boolean bdg = false
         String? keepdup
         Boolean? callsummits
         Int timeMinutes = 600  # Default to 10 hours