diff --git a/output.cc b/output.cc
index 6e14e7b6a..53ff07fa2 100644
--- a/output.cc
+++ b/output.cc
@@ -112,7 +112,6 @@
 #include <math.h>
 
 #include <set>
-#include <string>
 #include <vector>
 #include <list>
 
diff --git a/output.h b/output.h
index 8ad7450f7..08189c9dd 100644
--- a/output.h
+++ b/output.h
@@ -133,6 +133,8 @@
 #include "nmap.h"
 #include "global_structures.h"
 
+#include <string>
+
 #ifdef WIN32
 /* Display a warning that a device is not Ethernet and so raw sockets
    will be used. The warning is shown only once per unique device name. */