diff --git a/src/machine.h.in b/src/machine.h.in
index 8b1a41ab4659ca3dab0d0baa891b2738cf3982e5..7340070012e58764962a7f290352cacafb36c6b4 100644
--- a/src/machine.h.in
+++ b/src/machine.h.in
@@ -114,7 +114,7 @@
 #undef USE_IOCTL_FIONBIO
 #undef USE_FCNTL_O_NDELAY
 #undef USE_FCNTL_FNDELAY
-#undef USE_FCNTL_NONBLOCK
+#undef USE_FCNTL_O_NONBLOCK
 
 /* Define if you have index */
 #undef HAVE_STRTOL