diff --git a/reactos/drivers/lib/oskittcp/oskittcp.xml b/reactos/drivers/lib/oskittcp/oskittcp.xml
index ee1ee871f7d..a3e0f0a0e31 100644
--- a/reactos/drivers/lib/oskittcp/oskittcp.xml
+++ b/reactos/drivers/lib/oskittcp/oskittcp.xml
@@ -4,6 +4,7 @@
 	<define name="KERNEL"/>
 	<define name="_DISABLE_TIDENTS"/>
 	<define name="__USE_W32API"/>
+	<define name="__NO_CTYPE_INLINES" />
 	<include>drivers/lib/oskittcp/include/freebsd</include>
 	<include>drivers/lib/oskittcp/include/freebsd/sys/include</include>
 	<include>drivers/lib/oskittcp/include/freebsd/src/sys</include>