diff --git a/piker/tsp/_anal.py b/piker/tsp/_anal.py
index 42c3aa6c..26c3740e 100644
--- a/piker/tsp/_anal.py
+++ b/piker/tsp/_anal.py
@@ -578,11 +578,22 @@ def detect_time_gaps(
     # NOTE: this flag is to indicate that on this (sampling) time
     # scale we expect to only be filtering against larger venue
     # closures-scale time gaps.
+    #
+    # Map to total_ method since `dt_diff` is a duration type,
+    # not datetime - modern polars requires `total_*` methods
+    # for duration types (e.g. `total_days()` not `day()`)
+    # Ensure plural form for polars API (e.g. 'day' -> 'days')
+    unit_plural: str = (
+        gap_dt_unit
+        if gap_dt_unit.endswith('s')
+        else f'{gap_dt_unit}s'
+    )
+    duration_method: str = f'total_{unit_plural}'
     return step_gaps.filter(
         # Second by an arbitrary dt-unit step size
         getattr(
             pl.col('dt_diff').dt,
-            gap_dt_unit,
+            duration_method,
         )().abs() > gap_thresh
     )