diff --git a/src/tests/unit/machine-id.cpp b/src/tests/unit/machine-id.cpp
index 8131947..a875743 100644
--- a/src/tests/unit/machine-id.cpp
+++ b/src/tests/unit/machine-id.cpp
@@ -15,6 +15,7 @@
 #include "build-config.h"
 
 #include <iostream>
+#include <iomanip>
 #include <fstream>
 #include <string>
 #include <vector>