diff --git a/socket/socket_accept4.c b/socket/socket_accept4.c
index 61ced33..bb2ea11 100644
--- a/socket/socket_accept4.c
+++ b/socket/socket_accept4.c
@@ -3,6 +3,7 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 #endif
+#include <string.h>
 #include "windoze.h"
 #include "socket.h"
 #include "havesl.h"
diff --git a/socket/socket_accept6.c b/socket/socket_accept6.c
index 9aa2dcb..640a0f8 100644
--- a/socket/socket_accept6.c
+++ b/socket/socket_accept6.c
@@ -1,5 +1,6 @@
 #include <sys/param.h>
 #include <sys/types.h>
+#include <string.h>
 #ifndef __MINGW32__
 #include <sys/socket.h>
 #include <netinet/in.h>
diff --git a/socket/socket_deferaccept.c b/socket/socket_deferaccept.c
index 30c0d36..636c114 100644
--- a/socket/socket_deferaccept.c
+++ b/socket/socket_deferaccept.c
@@ -1,6 +1,7 @@
 #include "socket.h"
 
 #include <sys/types.h>
+#include <string.h>
 #ifndef __MINGW32__
 #include <sys/socket.h>
 #include <netinet/in.h>