diff --git a/cal_tools/cal_tools/agipdlib.py b/cal_tools/cal_tools/agipdlib.py
index b7281dd8dc26813ddc13ca847c848f885e0cadb5..5fbf7f6a6abe8f48dcd996fd41ce99ae3e482614 100644
--- a/cal_tools/cal_tools/agipdlib.py
+++ b/cal_tools/cal_tools/agipdlib.py
@@ -1162,7 +1162,7 @@ class AgipdCorrections:
         if np.count_nonzero(can_calibrate) == 0:
             return
         allcells = allcells[can_calibrate]
-        if self.valid_indices is not None:
+        if self.valid_indices is None:
             firange = np.arange(first_index, last_index)
         else:
             firange = self.valid_indices