diff --git a/scripts/pmt_hrv.py b/scripts/pmt_hrv.py
index 389f389e561ea38efb8e3a41157771bd081292de..feb22bd097d6d5ff62618d75fd5902cc90a2347b 100755
--- a/scripts/pmt_hrv.py
+++ b/scripts/pmt_hrv.py
@@ -89,6 +89,8 @@ class PMTHRV(kp.Module):
                 continue
             mean_hrv[i] = np.mean(self.hrv[i])
 
+        self.hrv = defaultdict(list)
+
         m[:, self.max_x - 1] = mean_hrv
         self.hrv_matrix = m