diff --git a/steps/interpolate_visibilities.cwl b/steps/interpolate_visibilities.cwl
index 91d5f5d32c5769b8b8cf6ff3ce372c92df0d52a6..e4dc74d9ce4d550912d61e62c7b4af6f66e98ced 100644
--- a/steps/interpolate_visibilities.cwl
+++ b/steps/interpolate_visibilities.cwl
@@ -6,37 +6,37 @@ id: interpolate_visibilities
 baseCommand:
   - DPPP
 arguments: 
-  - -msout.datacolumn=INTERP_DATA
-  - -msin.datacolumn=DATA
-  - steps=[interpolate]
+  - msout.datacolumn=INTERP_DATA
+  - msin.datacolumn=DATA
+  - steps=[interpolate] 
 inputs:
   - id: msin
     type: Directory
     inputBinding:
-      prefix: '-msin='
+      prefix: 'msin='
       separate: false
   - id: msout_name
     default: out.MS
     type: string
     inputBinding:
-      prefix: '-msout='
+      prefix: 'msout='
       separate: false
   - id: storage_manager
     type: string
     default: Dysco
     inputBinding:
       separate: false
-      prefix: '-msout.storagemanager='
+      prefix: 'msout.storagemanager='
   - id: storage_manager_databitrate
     type: int
     default: 0
     inputBinding:
-      prefix: '-msout.storagemanager.databitrate='
+      prefix: 'msout.storagemanager.databitrate='
       separate: false
   - id: window_size
     type: int
     inputBinding:
-      prefix: '-interpolate.windowsize='
+      prefix: 'interpolate.windowsize='
       separate: false
 
 outputs: