diff --git a/reactos/include/ndk/asm.h b/reactos/include/ndk/asm.h
index a4d348ac16b..241a9dcab0b 100644
--- a/reactos/include/ndk/asm.h
+++ b/reactos/include/ndk/asm.h
@@ -322,6 +322,20 @@ Author:
 #define CR0_CD                                  0x40000000
 #define CR0_PG                                  0x80000000
 
+//
+// CR4
+//
+#define CR4_VME                                 0x1
+#define CR4_PVI                                 0x2
+#define CR4_TSD                                 0x4
+#define CR4_DE                                  0x8
+#define CR4_PSE                                 0x10
+#define CR4_PAE                                 0x20
+#define CR4_MCE                                 0x40
+#define CR4_PGE                                 0x80
+#define CR4_FXSR                                0x200
+#define CR4_XMMEXCPT                            0x400
+
 //
 // Usermode callout frame definitions
 //