diff --git a/steps/find_skymodel_cal.cwl b/steps/find_skymodel_cal.cwl
index 552595ca5cc869147396fe87bda4ef708a9ed8d7..145448de34a13ad83f4b2c6494342f8afc32effd 100644
--- a/steps/find_skymodel_cal.cwl
+++ b/steps/find_skymodel_cal.cwl
@@ -9,6 +9,8 @@ inputs:
     - id: msin
       type: Directory[]
       doc: MSs containing the calibrator
+      inputBinding:
+        position: 0
     - id: skymodels
       type: Directory
       doc: Directory containing the sky models
@@ -20,12 +22,15 @@ label: find_skymodel_cal.py
 arguments:
   - '-c'
   - |
+    from unittest.mock import MagicMock
+    sys.modules['lofarpipe.support.data_map'] = MagicMock()
+    
+    import sys
+
     from find_skymodel_cal import main as find_skymodel
     import json
-    mss = list(
-          map(lambda x: x['path'],
-          filter(lambda x: x['class'] == 'Directory', $(inputs.msin))))
-    skymodels = $(inputs.skymodels)['path']
+    mss = sys.argv[1:]
+    skymodels = "$(inputs.skymodels.path)"
 
     extension = "$(inputs.skymodels_extension)"
     output = {}
@@ -50,4 +55,4 @@ requirements:
 
 hints:
   DockerRequirement:
-    dockerPull: lofar/lofar-pipeline
+    dockerPull: lofareosc/prefactor-ci