diff --git a/pyconfig.h.in b/pyconfig.h.in
index 771cd38..cfc84a5 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -825,6 +825,9 @@
 /* Define to 1 if you have the <sys/select.h> header file. */
 #undef HAVE_SYS_SELECT_H
 
+/* Define to 1 if you have the <sys/sendfile.h> header file. */
+#undef HAVE_SYS_SENDFILE_H
+
 /* Define to 1 if you have the <sys/socket.h> header file. */
 #undef HAVE_SYS_SOCKET_H