diff --git a/examples/ttl_in.py b/examples/ttl_in.py
index a35bd08..320eabd 100644
--- a/examples/ttl_in.py
+++ b/examples/ttl_in.py
@@ -51,6 +51,9 @@ class ExternalTrigger(EnvExperiment):
         self.ttlout.pulse(1*us)
 
 
+import time
+
+
 class MeanTimestampDuration(EnvExperiment):
     def build(self):
         self.setattr_device("core")