diff --git a/tests/sys/fs/fusefs/io.cc b/tests/sys/fs/fusefs/io.cc
--- a/tests/sys/fs/fusefs/io.cc
+++ b/tests/sys/fs/fusefs/io.cc
@@ -38,6 +38,8 @@
 #include <unistd.h>
 }
 
+#include <iomanip>
+
 #include "mockfs.hh"
 #include "utils.hh"