diff --git a/example/kalman/ukf-linear-example.cpp b/example/kalman/ukf-linear-example.cpp
index 003e043552..5675972ae6 100644
--- a/example/kalman/ukf-linear-example.cpp
+++ b/example/kalman/ukf-linear-example.cpp
@@ -56,6 +56,8 @@
  * not perfect.
 */
 
+#include <iostream>
+
 // UKF includes
 #include <visp3/core/vpUKSigmaDrawerMerwe.h>
 #include <visp3/core/vpUnscentedKalman.h>