diff --git a/src/x_to_nwb/hr_segments.py b/src/x_to_nwb/hr_segments.py
index f172ace..a17a848 100644
--- a/src/x_to_nwb/hr_segments.py
+++ b/src/x_to_nwb/hr_segments.py
@@ -161,7 +161,11 @@ def calculateNumberOfPoints(self, duration):
         """
         Return the number of points of this segment.
         """
-        return math.trunc(duration / self.sampleInterval)
+        num_points = duration / self.sampleInterval
+        num_points_int = int(np.round(num_points))
+        if not math.isclose(num_points, num_points_int):
+            raise ValueError(f"Segment duration {duration} is not divisible by sample interval {self.sampleInterval}")
+        return num_points_int
 
     def getAmplitude(self, channelRec, segmentRec):
         """