diff --git a/reactos/lib/rossym/initkm.c b/reactos/lib/rossym/initkm.c
index c6981391570..d2fd1df887e 100644
--- a/reactos/lib/rossym/initkm.c
+++ b/reactos/lib/rossym/initkm.c
@@ -15,6 +15,7 @@
 #define NDEBUG
 #include <debug.h>
 
+#define TAG(A, B, C, D) (ULONG)(((A)<<0) + ((B)<<8) + ((C)<<16) + ((D)<<24))
 #define TAG_ROSSYM TAG('R', 'S', 'Y', 'M')
 
 static PVOID
diff --git a/reactos/lib/rtl/rtl.h b/reactos/lib/rtl/rtl.h
index 1b4258ea4ac..54121ba722e 100644
--- a/reactos/lib/rtl/rtl.h
+++ b/reactos/lib/rtl/rtl.h
@@ -24,6 +24,7 @@
 #include <ntos.h>
 #include <stdio.h>
 
+#define TAG(A, B, C, D) (ULONG)(((A)<<0) + ((B)<<8) + ((C)<<16) + ((D)<<24))
 #define ROUNDUP(a,b)    ((((a)+(b)-1)/(b))*(b))
 #ifndef HIWORD
 #define HIWORD(l) ((WORD)(((DWORD)(l) >> 16) & 0xFFFF))