diff --git a/xfel_calibrate/calibrate.py b/xfel_calibrate/calibrate.py
index fd3321668913b1b6b617f9462f692c44f3ddc059..36647f07cc8c8764c0587e764b756e10373c04b5 100755
--- a/xfel_calibrate/calibrate.py
+++ b/xfel_calibrate/calibrate.py
@@ -272,7 +272,7 @@ elif len(sys.argv) >= 3:
                                         help=helpstr,
                                         required=required)
             
-        do_parse(nb, parser, True)
+        do_parse(nb, parser, (ext_func is not None))
         
         # extend parameters if needed
         ext_func = notebooks[detector][caltype].get("extend parms", None)