diff --git a/win32/ruby.def b/win32/ruby.def
index ae4b9d6889..54581882f5 100644
--- a/win32/ruby.def
+++ b/win32/ruby.def
@@ -125,6 +125,7 @@ EXPORTS
 	mybind
 	myconnect
 	myfdset
+	myfdclr
 	myfdisset
 	myselect
 	mygetpeername
diff --git a/win32/win32.h b/win32/win32.h
index 412f8f9278..c44cf73b07 100644
--- a/win32/win32.h
+++ b/win32/win32.h
@@ -176,6 +176,7 @@ extern SOCKET  myaccept(SOCKET, struct sockaddr *, int *);
 extern int  mybind(SOCKET, struct sockaddr *, int);
 extern int  myconnect(SOCKET, struct sockaddr *, int);
 extern void myfdset(int, fd_set*);
+extern void myfdclr(int, fd_set*);
 extern int  myfdisset(int, fd_set*);
 extern long myselect(int, fd_set *, fd_set *, fd_set *, struct timeval *);
 extern int  mygetpeername(SOCKET, struct sockaddr *, int *);