diff --git a/src/xfel_calibrate/calibrate.py b/src/xfel_calibrate/calibrate.py
index c4b8b76bf1265df33c69cf7f94f441e3fdfe2411..5590e4c34f5f6c9c10d3700260adfb3c3e1ea2f2 100755
--- a/src/xfel_calibrate/calibrate.py
+++ b/src/xfel_calibrate/calibrate.py
@@ -770,6 +770,9 @@ def run(argv=None):
         cvtype = get_par_attr(parms, concurrency_par, 'type', list)
         cvals = remove_duplications(cvals)
 
+        if not cvals:
+            raise ValueError("Splitting data for concurrency gave 0 jobs")
+
         for cnum, cval in enumerate(cvals):
             show_title = cnum == 0
             cval = [cval, ] if not isinstance(cval, list) and cvtype is list else cval