diff --git a/test/prsim_plot.py b/test/prsim_plot.py
index 8dd0a07..2e822fd 100755
--- a/test/prsim_plot.py
+++ b/test/prsim_plot.py
@@ -119,6 +119,7 @@ Use -exclude='regex' to specify signals to exclude (or -ex).""")
 	# Get list of all times (after filtering)
 	times = np.array([int(e[0]) for e in entries])
 	if not include_all_times: unique_times = np.unique(times)
+	num_times = unique_times.shape[0]
 
 	# Get list of all sigs
 	sigs = np.array([e[1] for e in entries])