diff --git a/rt_eqcorrscan/reactor/backfill.py b/rt_eqcorrscan/reactor/backfill.py
index 4b395d6..f6f31ff 100644
--- a/rt_eqcorrscan/reactor/backfill.py
+++ b/rt_eqcorrscan/reactor/backfill.py
@@ -123,7 +123,7 @@ def backfill(
                 parallel_process=parallel_processing,
                 process_cores=process_cores, copy_data=False,
                 ignore_bad_data=True,
-                overlap=0,
+                overlap=None,
                 **kwargs)
             Logger.info(f"Backfiller made {len(new_party)} detections between {_starttime} and {_endtime}")
         except Exception as e:
diff --git a/rt_eqcorrscan/rt_match_filter.py b/rt_eqcorrscan/rt_match_filter.py
index da7bcba..e6ebaa7 100644
--- a/rt_eqcorrscan/rt_match_filter.py
+++ b/rt_eqcorrscan/rt_match_filter.py
@@ -885,7 +885,7 @@ def run(
                             process_cores=self.process_cores,
                             parallel_process=self._parallel_processing,
                             ignore_bad_data=True, copy_data=False,
-                            concurrent_processing=False, overlap=0,
+                            concurrent_processing=False, overlap=None,
                             **kwargs)
                         Logger.info("Completed detection")
                     except Exception as e:  # pragma: no cover