diff --git a/steps/blsmooth.cwl b/steps/blsmooth.cwl
index 7748ae8ed68f66ee3d2694df79fc3e24e634ba15..e2fbdd1abc61caf81353b645d4d413f2de07e24d 100644
--- a/steps/blsmooth.cwl
+++ b/steps/blsmooth.cwl
@@ -22,7 +22,7 @@ inputs:
     type: boolean
     doc: 'If true performs smoothing'
     inputBinding:
-      prefix: '--smooth='
+      prefix: -S=
       valueFrom: "$(self ? 'True': 'False')"
       separate: false