diff --git a/Pose2Sim/calibration.py b/Pose2Sim/calibration.py
index b606dda..0ca8f1b 100644
--- a/Pose2Sim/calibration.py
+++ b/Pose2Sim/calibration.py
@@ -50,6 +50,7 @@ from mpl_interactions import zoom_factory, panhandler
 from PIL import Image
 from contextlib import contextmanager,redirect_stderr,redirect_stdout
 from os import devnull
+import tkinter
 
 
 ## AUTHORSHIP INFORMATION