diff --git a/steps/blsmooth.cwl b/steps/blsmooth.cwl
index fdd8485a32735b82eb32c7f5f4c5bb31858fd6d1..7748ae8ed68f66ee3d2694df79fc3e24e634ba15 100644
--- a/steps/blsmooth.cwl
+++ b/steps/blsmooth.cwl
@@ -22,7 +22,9 @@ inputs:
     type: boolean
     doc: 'If true performs smoothing'
     inputBinding:
-      prefix: '--smooth=SMOOTH'
+      prefix: '--smooth='
+      valueFrom: "$(self ? 'True': 'False')"
+      separate: false
 
   - default: 0.5
     id: bscalefactor