diff --git a/mk/re.mk b/mk/re.mk
index 5540601..d92bf26 100644
--- a/mk/re.mk
+++ b/mk/re.mk
@@ -292,7 +292,7 @@ ifeq ($(OS),openbsd)
 	HAVE_KQUEUE	:= 1
 endif
 ifeq ($(OS),win32)
-	CFLAGS		+= -DWIN32 -D_WIN32_WINNT=0x0501
+	CFLAGS		+= -DWIN32 -D_WIN32_WINNT=0x0501 -D__ssize_t_defined
 	LIBS		+= -lwsock32 -lws2_32 -liphlpapi
 	LFLAGS		+=
 	SH_LFLAGS	+= -shared