diff --git a/reactos/lib/ntdll/ntdll.xml b/reactos/lib/ntdll/ntdll.xml
index a49ffa18be1..5e23933cf03 100644
--- a/reactos/lib/ntdll/ntdll.xml
+++ b/reactos/lib/ntdll/ntdll.xml
@@ -7,6 +7,7 @@
 	<define name="__USE_W32API" />
 	<define name="_WIN32_WINNT">0x0502</define>
 	<define name="_NTOSKRNL_" />
+	<define name="__NO_CTYPE_INLINES" />
 	<library>rtl</library>
 	<library>intrlck</library>
 	<library>string</library>