diff --git a/workflows/prefactor_calibrator.cwl b/workflows/prefactor_calibrator.cwl
index e3d0d939e5e0699bc019d674014f645a10794cde..55e36d986293cec07f7b503e5dbab0f565fc0123 100644
--- a/workflows/prefactor_calibrator.cwl
+++ b/workflows/prefactor_calibrator.cwl
@@ -55,7 +55,8 @@ inputs:
     'sbg:x': -89
     'sbg:y': -276
   - id: min_separation
-    type: float?
+    type: float
+    default: 20.
     'sbg:x': -638.4987182617188
     'sbg:y': 31.238996505737305
   - id: A-Team_sky_model