diff --git a/impatient b/impatient
index b285cf7..0240e7e 100755
--- a/impatient
+++ b/impatient
@@ -132,6 +132,11 @@ while True:
             ), end='')
     sys.stdout.flush()
 
-    if final and current >= args.termination_value_threshold*final and all(d == 0 for d in deltas[-args.termination_inactivity_threshold:]):
+    if (
+        final
+        and current >= args.termination_value_threshold*final
+        and len(deltas) >= args.termination_inactivity_threshold
+        and all(d == 0 for d in deltas[-args.termination_inactivity_threshold:])
+    ):
         print()
         break