diff --git a/os/io.c b/os/io.c
index 53b37b7ce..64b64ae75 100644
--- a/os/io.c
+++ b/os/io.c
@@ -105,7 +105,7 @@ static OsCommPtr AvailableInput = (OsCommPtr)NULL;
 #define get_req_len(req,cli) ((cli)->swapped ? \
 			      lswaps((req)->length) : (req)->length)
 
-#include <X11/extensions/bigreqstr.h>
+#include <X11/extensions/bigreqsproto.h>
 
 #define get_big_req_len(req,cli) ((cli)->swapped ? \
 				  lswapl(((xBigReq *)(req))->length) : \