diff --git a/usr.bin/gprof/aout.c b/usr.bin/gprof/aout.c
index 2ccf818f42e..9103148997d 100644
--- a/usr.bin/gprof/aout.c
+++ b/usr.bin/gprof/aout.c
@@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
 
 #include <a.out.h>
 #include <err.h>
+#include <string.h>
 
 #include "gprof.h"