diff --git a/src/mt/process-list.cpp b/src/mt/process-list.cpp
index b0d37b4ecabd38c982d62ca89a32bb8dba183a79..14fa05f63f9db18dc1785bb67fe5d2d893352dfe 100644
--- a/src/mt/process-list.cpp
+++ b/src/mt/process-list.cpp
@@ -2,6 +2,7 @@
  * Author: O. Stasse, 2019
  * See LICENSE file in the root directory of this repository.
  */
+#include <iostream>
 #include <fstream>
 #include <sstream>
 #include <string>