diff --git a/reactos/ntoskrnl/include/internal/amd64/mm.h b/reactos/ntoskrnl/include/internal/amd64/mm.h
index fa8da9a6434..e9a415f99e7 100644
--- a/reactos/ntoskrnl/include/internal/amd64/mm.h
+++ b/reactos/ntoskrnl/include/internal/amd64/mm.h
@@ -6,7 +6,13 @@
 #define __NTOSKRNL_INCLUDE_INTERNAL_AMD64_MM_H
 
 struct _EPROCESS;
-PULONG_PTR MmGetPageDirectory(VOID);
+
+PULONG64
+FORCEINLINE
+MmGetPageDirectory(VOID)
+{
+    return (PULONG64)__readcr3();
+}
 
 #define PAGE_MASK(x)		((x)&(~0xfff))
 #define PAE_PAGE_MASK(x)	((x)&(~0xfffLL))