diff --git a/scripts/ztplot.py b/scripts/ztplot.py
index e7ec5c530523f42578293c61f9bded41cab7bb43..11a8628edea29e8573d0d2364b3325274e348c7b 100755
--- a/scripts/ztplot.py
+++ b/scripts/ztplot.py
@@ -96,8 +96,8 @@ class ZTPlot(Module):
         hits = self.calib.apply(hits)
         event_info = blob['EventInfo']
 
-        n_triggered_dus = np.unique(hits[hits.triggered == True].du)
-        if n_triggered_dus < self.min_dus:
+        triggered_dus = np.unique(hits[hits.triggered == True].du)
+        if len(triggered_dus) < self.min_dus:
             print("Skipping...")
             return blob