diff --git a/SQCSim-common/define.h b/SQCSim-common/define.h
index 9cb966e..b716121 100644
--- a/SQCSim-common/define.h
+++ b/SQCSim-common/define.h
@@ -47,7 +47,7 @@ typedef uint64_t Timestamp;
 #include <ctime>
 
 #define ioctl ioctlsocket
-#define O_NONBLOCK FIONBIO
+#define SOCK_NONBLOCK FIONBIO
 #define strcpy strcpy_s
 #define addrlen_t int
 #define popen _popen