diff --git a/src/toolbox_scs/misc/bunch_pattern.py b/src/toolbox_scs/misc/bunch_pattern.py
index 6431fd1f648b43d5c69ef50cfc3c6c36b2a9e72c..a698fe3ffb65599c0d57407ef70b6bc53582c052 100644
--- a/src/toolbox_scs/misc/bunch_pattern.py
+++ b/src/toolbox_scs/misc/bunch_pattern.py
@@ -178,7 +178,7 @@ def load_bpt(run, merge_with=None, run_mnemonics=None):
                                 name='bunchPatternTable')
             log.debug(f'Loaded {key} from DataCollection.')
             if merge_with is not None:
-                merge_with = merge_with.merge(bpt, join='inner')
+                merge_with.update(merge_with.merge(bpt, join='inner'))
             return bpt
     log.debug('Could not find bunch pattern table.')
     return None