diff --git a/reactos/ntoskrnl/include/internal/mm.h b/reactos/ntoskrnl/include/internal/mm.h
index 3c67357ae7b..6ec931514bf 100644
--- a/reactos/ntoskrnl/include/internal/mm.h
+++ b/reactos/ntoskrnl/include/internal/mm.h
@@ -6,22 +6,22 @@
 
 struct _EPROCESS;
 
-extern ULONG MiFreeSwapPages;
-extern ULONG MiUsedSwapPages;
-extern ULONG MmPagedPoolSize;
-extern ULONG MmTotalPagedPoolQuota;
-extern ULONG MmTotalNonPagedPoolQuota;
+extern PFN_NUMBER MiFreeSwapPages;
+extern PFN_NUMBER MiUsedSwapPages;
+extern SIZE_T MmPagedPoolSize;
+extern SIZE_T MmTotalPagedPoolQuota;
+extern SIZE_T MmTotalNonPagedPoolQuota;
 extern PHYSICAL_ADDRESS MmSharedDataPagePhysicalAddress;
-extern ULONG MmNumberOfPhysicalPages;
+extern PFN_NUMBER MmNumberOfPhysicalPages;
 extern UCHAR MmDisablePagingExecutive;
-extern ULONG MmLowestPhysicalPage;
-extern ULONG MmHighestPhysicalPage;
-extern ULONG MmAvailablePages;
-extern ULONG MmResidentAvailablePages;
-extern ULONG MmNumberOfSystemPtes;
+extern PFN_NUMBER MmLowestPhysicalPage;
+extern PFN_NUMBER MmHighestPhysicalPage;
+extern PFN_NUMBER MmAvailablePages;
+extern PFN_NUMBER MmResidentAvailablePages;
+extern ULONG_PTR MmNumberOfSystemPtes;
 
 extern PVOID MmPagedPoolBase;
-extern ULONG MmPagedPoolSize;
+extern SIZE_T MmPagedPoolSize;
 
 extern PMEMORY_ALLOCATION_DESCRIPTOR MiFreeDescriptor;
 extern MEMORY_ALLOCATION_DESCRIPTOR MiFreeDescriptorOrg;
diff --git a/reactos/ntoskrnl/io/iomgr/iocomp.c b/reactos/ntoskrnl/io/iomgr/iocomp.c
index f695ea01c55..dfb771394fa 100644
--- a/reactos/ntoskrnl/io/iomgr/iocomp.c
+++ b/reactos/ntoskrnl/io/iomgr/iocomp.c
@@ -92,7 +92,7 @@ IopFreeMiniPacket(PIOP_MINI_COMPLETION_PACKET Packet)
     }
 
     /* The free was within dhe Depth */
-    InterlockedPushEntrySList(&List->L.ListHead, (PSINGLE_LIST_ENTRY)Packet);
+    InterlockedPushEntrySList(&List->L.ListHead, (PSLIST_ENTRY)Packet);
 }
 
 VOID
diff --git a/reactos/ntoskrnl/io/iomgr/irp.c b/reactos/ntoskrnl/io/iomgr/irp.c
index 598f53d4fe9..1d870a04668 100644
--- a/reactos/ntoskrnl/io/iomgr/irp.c
+++ b/reactos/ntoskrnl/io/iomgr/irp.c
@@ -1553,7 +1553,7 @@ IoFreeIrp(IN PIRP Irp)
         if (Irp)
         {
            InterlockedPushEntrySList(&List->L.ListHead,
-                                     (PSINGLE_LIST_ENTRY)Irp);
+                                     (PSLIST_ENTRY)Irp);
         }
     }
 }
diff --git a/reactos/ntoskrnl/ke/bug.c b/reactos/ntoskrnl/ke/bug.c
index 6aef75230bb..108fb4690b8 100644
--- a/reactos/ntoskrnl/ke/bug.c
+++ b/reactos/ntoskrnl/ke/bug.c
@@ -1411,7 +1411,7 @@ KeRegisterNmiCallback(IN PNMI_CALLBACK CallbackRoutine,
     //
     KiAcquireNmiListLock(&OldIrql);
     NmiData->Next = KiNmiCallbackListHead;
-    Next = InterlockedCompareExchangePointer(&KiNmiCallbackListHead,
+    Next = InterlockedCompareExchangePointer((PVOID*)&KiNmiCallbackListHead,
                                              NmiData,
                                              NmiData->Next);
     ASSERT(Next == NmiData->Next);
diff --git a/reactos/ntoskrnl/mm/ARM3/contmem.c b/reactos/ntoskrnl/mm/ARM3/contmem.c
index 645d973b367..a92a47c147a 100644
--- a/reactos/ntoskrnl/mm/ARM3/contmem.c
+++ b/reactos/ntoskrnl/mm/ARM3/contmem.c
@@ -391,7 +391,7 @@ MmAllocateContiguousMemorySpecifyCache(IN SIZE_T NumberOfBytes,
  */
 PVOID
 NTAPI
-MmAllocateContiguousMemory(IN ULONG NumberOfBytes,
+MmAllocateContiguousMemory(IN SIZE_T NumberOfBytes,
                            IN PHYSICAL_ADDRESS HighestAcceptableAddress)
 {
     PFN_NUMBER HighestPfn;
diff --git a/reactos/ntoskrnl/mm/ARM3/iosup.c b/reactos/ntoskrnl/mm/ARM3/iosup.c
index b9f7eb641d9..03cd94ec760 100644
--- a/reactos/ntoskrnl/mm/ARM3/iosup.c
+++ b/reactos/ntoskrnl/mm/ARM3/iosup.c
@@ -46,7 +46,7 @@ MI_PFN_CACHE_ATTRIBUTE MiPlatformCacheAttributes[2][MmMaximumCacheType] =
 PVOID
 NTAPI
 MmMapIoSpace(IN PHYSICAL_ADDRESS PhysicalAddress,
-             IN ULONG NumberOfBytes,
+             IN SIZE_T NumberOfBytes,
              IN MEMORY_CACHING_TYPE CacheType)
 {
     
diff --git a/reactos/ntoskrnl/mm/ARM3/miarm.h b/reactos/ntoskrnl/mm/ARM3/miarm.h
index 85137632e03..67fe723f8a1 100644
--- a/reactos/ntoskrnl/mm/ARM3/miarm.h
+++ b/reactos/ntoskrnl/mm/ARM3/miarm.h
@@ -33,6 +33,8 @@
 #define MI_NONPAGED_POOL_END                   (PVOID)0xFFBE0000
 #define MI_DEBUG_MAPPING                       (PVOID)0xFFBFF000
 
+#endif /* !_M_AMD64 */
+
 #define MI_MIN_SECONDARY_COLORS                 8
 #define MI_SECONDARY_COLORS                     64
 #define MI_MAX_SECONDARY_COLORS                 1024
@@ -42,10 +44,10 @@
 
 /* Make the code cleaner with some definitions for size multiples */
 #define _1KB (1024)
-#define _1MB (1000 * _1KB)
+#define _1MB (1024 * _1KB)
 
-/* Size of a PDE directory, and size of a page table */
-#define PDE_SIZE (PDE_COUNT * sizeof(MMPDE))
+/* Size of a page directory, and size of a page table */
+#define PD_SIZE (PDE_COUNT * sizeof(MMPDE))
 #define PT_SIZE  (PTE_COUNT * sizeof(MMPTE))
 
 /* Architecture specific count of PDEs in a directory, and count of PTEs in a PT */
@@ -53,7 +55,11 @@
 #define PD_COUNT  1
 #define PDE_COUNT 1024
 #define PTE_COUNT 1024
-#elif _M_ARM
+#elif defined(_M_AMD64)
+#define PD_COUNT  (512 * 512)
+#define PDE_COUNT 512
+#define PTE_COUNT 512
+#elif defined(_M_ARM)
 #define PD_COUNT  1
 #define PDE_COUNT 4096
 #define PTE_COUNT 256
@@ -73,8 +79,6 @@
 #define BASE_POOL_TYPE_MASK 1
 #define POOL_MAX_ALLOC (PAGE_SIZE - (sizeof(POOL_HEADER) + sizeof(LIST_ENTRY)))
 
-#endif
-
 typedef struct _POOL_DESCRIPTOR
 {
     POOL_TYPE PoolType;
@@ -196,24 +200,24 @@ extern MMPTE HyperTemplatePte;
 extern MMPTE ValidKernelPde;
 extern MMPTE ValidKernelPte;
 
-extern ULONG_PTR MmSizeOfNonPagedPoolInBytes;
-extern ULONG_PTR MmMaximumNonPagedPoolInBytes;
+extern SIZE_T MmSizeOfNonPagedPoolInBytes;
+extern SIZE_T MmMaximumNonPagedPoolInBytes;
 extern PFN_NUMBER MmMaximumNonPagedPoolInPages;
 extern PFN_NUMBER MmSizeOfPagedPoolInPages;
 extern PVOID MmNonPagedSystemStart;
 extern PVOID MmNonPagedPoolStart;
 extern PVOID MmNonPagedPoolExpansionStart;
 extern PVOID MmNonPagedPoolEnd;
-extern ULONG_PTR MmSizeOfPagedPoolInBytes;
+extern SIZE_T MmSizeOfPagedPoolInBytes;
 extern PVOID MmPagedPoolStart;
 extern PVOID MmPagedPoolEnd;
 extern PVOID MmSessionBase;
-extern ULONG_PTR MmSessionSize;
+extern SIZE_T MmSessionSize;
 extern PMMPTE MmFirstReservedMappingPte, MmLastReservedMappingPte;
 extern PMMPTE MiFirstReservedZeroingPte;
 extern MI_PFN_CACHE_ATTRIBUTE MiPlatformCacheAttributes[2][MmMaximumCacheType];
 extern PPHYSICAL_MEMORY_DESCRIPTOR MmPhysicalMemoryBlock;
-extern ULONG_PTR MmBootImageSize;
+extern SIZE_T MmBootImageSize;
 extern PMMPTE MmSystemPtesStart[MaximumPtePoolTypes];
 extern PMMPTE MmSystemPtesEnd[MaximumPtePoolTypes];
 extern PMEMORY_ALLOCATION_DESCRIPTOR MxFreeDescriptor;
@@ -226,10 +230,9 @@ extern PVOID MmPagedPoolStart;
 extern PVOID MmPagedPoolEnd;
 extern PVOID MmNonPagedSystemStart;
 extern PVOID MiSystemViewStart;
-extern ULONG_PTR MmSystemViewSize;
+extern SIZE_T MmSystemViewSize;
 extern PVOID MmSessionBase;
 extern PVOID MiSessionSpaceEnd;
-extern ULONG_PTR MmSizeOfPagedPoolInBytes;
 extern PMMPTE MmSystemPagePtes;
 extern PVOID MmSystemCacheStart;
 extern PVOID MmSystemCacheEnd;
@@ -239,13 +242,12 @@ extern ULONG_PTR MmSubsectionBase;
 extern ULONG MmSpecialPoolTag;
 extern PVOID MmHyperSpaceEnd;
 extern PMMWSL MmSystemCacheWorkingSetList;
-extern ULONG MmMinimumNonPagedPoolSize;
+extern SIZE_T MmMinimumNonPagedPoolSize;
 extern ULONG MmMinAdditionNonPagedPoolPerMb;
-extern ULONG MmDefaultMaximumNonPagedPool;
+extern SIZE_T MmDefaultMaximumNonPagedPool;
 extern ULONG MmMaxAdditionNonPagedPoolPerMb;
 extern ULONG MmSecondaryColors;
 extern ULONG MmSecondaryColorMask;
-extern ULONG MmNumberOfSystemPtes;
 extern ULONG MmMaximumNonPagedPoolPercent;
 extern ULONG MmLargeStackSize;
 extern PMMCOLOR_TABLES MmFreePagesByColor[FreePageList + 1];
diff --git a/reactos/ntoskrnl/mm/ARM3/mminit.c b/reactos/ntoskrnl/mm/ARM3/mminit.c
index 89d082e4f95..39e3c3e898b 100644
--- a/reactos/ntoskrnl/mm/ARM3/mminit.c
+++ b/reactos/ntoskrnl/mm/ARM3/mminit.c
@@ -23,8 +23,8 @@
 // figure out the most appropriate values.
 //
 ULONG MmMaximumNonPagedPoolPercent;
-ULONG MmSizeOfNonPagedPoolInBytes;
-ULONG MmMaximumNonPagedPoolInBytes;
+SIZE_T MmSizeOfNonPagedPoolInBytes;
+SIZE_T MmMaximumNonPagedPoolInBytes;
 
 /* Some of the same values, in pages */
 PFN_NUMBER MmMaximumNonPagedPoolInPages;
@@ -36,9 +36,9 @@ PFN_NUMBER MmMaximumNonPagedPoolInPages;
 // They are described on http://support.microsoft.com/default.aspx/kb/126402/ja
 // along with the algorithm that uses them, which is implemented later below.
 //
-ULONG MmMinimumNonPagedPoolSize = 256 * 1024;
+SIZE_T MmMinimumNonPagedPoolSize = 256 * 1024;
 ULONG MmMinAdditionNonPagedPoolPerMb = 32 * 1024;
-ULONG MmDefaultMaximumNonPagedPool = 1024 * 1024; 
+SIZE_T MmDefaultMaximumNonPagedPool = 1024 * 1024; 
 ULONG MmMaxAdditionNonPagedPoolPerMb = 400 * 1024;
 
 //
@@ -107,7 +107,7 @@ PVOID MmPagedPoolEnd;
 //
 // And this is its default size
 //
-ULONG MmSizeOfPagedPoolInBytes = MI_MIN_INIT_PAGED_POOLSIZE;
+SIZE_T MmSizeOfPagedPoolInBytes = MI_MIN_INIT_PAGED_POOLSIZE;
 PFN_NUMBER MmSizeOfPagedPoolInPages = MI_MIN_INIT_PAGED_POOLSIZE / PAGE_SIZE;
 
 //
@@ -131,10 +131,10 @@ PVOID MiSessionViewStart;   // 0xBE000000
 PVOID MiSessionPoolEnd;     // 0xBE000000
 PVOID MiSessionPoolStart;   // 0xBD000000
 PVOID MmSessionBase;        // 0xBD000000
-ULONG MmSessionSize;
-ULONG MmSessionViewSize;
-ULONG MmSessionPoolSize;
-ULONG MmSessionImageSize;
+SIZE_T MmSessionSize;
+SIZE_T MmSessionViewSize;
+SIZE_T MmSessionPoolSize;
+SIZE_T MmSessionImageSize;
 
 //
 // The system view space, on the other hand, is where sections that are memory
@@ -143,7 +143,7 @@ ULONG MmSessionImageSize;
 // By default, it is a 16MB region.
 //
 PVOID MiSystemViewStart;
-ULONG MmSystemViewSize;
+SIZE_T MmSystemViewSize;
 
 //
 // A copy of the system page directory (the page directory associated with the
@@ -167,13 +167,13 @@ PMMWSL MmSystemCacheWorkingSetList = MI_SYSTEM_CACHE_WS_START;
 // On systems with more than 32MB, this number is then doubled, and further
 // aligned up to a PDE boundary (4MB).
 //
-ULONG MmNumberOfSystemPtes;
+ULONG_PTR MmNumberOfSystemPtes;
 
 //
 // This is how many pages the PFN database will take up
 // In Windows, this includes the Quark Color Table, but not in ARM³
 //
-ULONG MxPfnAllocation;
+PFN_NUMBER MxPfnAllocation;
 
 //
 // Unlike the old ReactOS Memory Manager, ARM³ (and Windows) does not keep track
@@ -197,7 +197,7 @@ PPHYSICAL_MEMORY_DESCRIPTOR MmPhysicalMemoryBlock;
 //
 // This is where we keep track of the most basic physical layout markers
 //
-ULONG MmNumberOfPhysicalPages, MmHighestPhysicalPage, MmLowestPhysicalPage = -1;
+PFN_NUMBER MmNumberOfPhysicalPages, MmHighestPhysicalPage, MmLowestPhysicalPage = -1;
 
 //
 // The total number of pages mapped by the boot loader, which include the kernel
@@ -207,13 +207,13 @@ ULONG MmNumberOfPhysicalPages, MmHighestPhysicalPage, MmLowestPhysicalPage = -1;
 //
 // This number is later aligned up to a PDE boundary.
 //
-ULONG MmBootImageSize;
+SIZE_T MmBootImageSize;
 
 //
 // These three variables keep track of the core separation of address space that
 // exists between kernel mode and user mode.
 //
-ULONG MmUserProbeAddress;
+ULONG_PTR MmUserProbeAddress;
 PVOID MmHighestUserAddress;
 PVOID MmSystemRangeStart;
 
diff --git a/reactos/ntoskrnl/mm/ARM3/ncache.c b/reactos/ntoskrnl/mm/ARM3/ncache.c
index f43d10afd51..6f8376fe264 100644
--- a/reactos/ntoskrnl/mm/ARM3/ncache.c
+++ b/reactos/ntoskrnl/mm/ARM3/ncache.c
@@ -23,7 +23,7 @@
  */
 PVOID
 NTAPI
-MmAllocateNonCachedMemory(IN ULONG NumberOfBytes)
+MmAllocateNonCachedMemory(IN SIZE_T NumberOfBytes)
 {
     PFN_NUMBER PageCount, MdlPageCount, PageFrameIndex;
     PHYSICAL_ADDRESS LowAddress, HighAddress, SkipBytes;
diff --git a/reactos/ntoskrnl/mm/ARM3/procsup.c b/reactos/ntoskrnl/mm/ARM3/procsup.c
index 24bd11a2586..b95098dc507 100644
--- a/reactos/ntoskrnl/mm/ARM3/procsup.c
+++ b/reactos/ntoskrnl/mm/ARM3/procsup.c
@@ -503,7 +503,7 @@ MmCreatePeb(IN PEPROCESS Process,
             ImageConfigData = RtlImageDirectoryEntryToData(Peb->ImageBaseAddress,
                                                            TRUE,
                                                            IMAGE_DIRECTORY_ENTRY_LOAD_CONFIG,
-                                                           &ViewSize);
+                                                           (PULONG)&ViewSize);
             if (ImageConfigData)
             {
                 //
diff --git a/reactos/ntoskrnl/mm/ARM3/virtual.c b/reactos/ntoskrnl/mm/ARM3/virtual.c
index 88ff54f5dcc..10c1f1bba60 100644
--- a/reactos/ntoskrnl/mm/ARM3/virtual.c
+++ b/reactos/ntoskrnl/mm/ARM3/virtual.c
@@ -775,7 +775,7 @@ NtWriteVirtualMemory(IN HANDLE ProcessHandle,
     KPROCESSOR_MODE PreviousMode = ExGetPreviousMode();
     PEPROCESS Process;
     NTSTATUS Status = STATUS_SUCCESS;
-    ULONG BytesWritten = 0;
+    SIZE_T BytesWritten = 0;
     PAGED_CODE();
 
     //
diff --git a/reactos/ntoskrnl/mm/balance.c b/reactos/ntoskrnl/mm/balance.c
index d786f768e3a..555c7a666db 100644
--- a/reactos/ntoskrnl/mm/balance.c
+++ b/reactos/ntoskrnl/mm/balance.c
@@ -228,7 +228,7 @@ MiIsBalancerThread(VOID)
           PsGetCurrentThread() == MiBalancerThreadId.UniqueThread;
 }
 
-VOID NTAPI MiSetConsumer(IN PFN_TYPE Pfn, IN ULONG Consumer);
+VOID NTAPI MiSetConsumer(IN PFN_NUMBER Pfn, IN ULONG Consumer);
 
 NTSTATUS
 NTAPI
diff --git a/reactos/ntoskrnl/mm/pagefile.c b/reactos/ntoskrnl/mm/pagefile.c
index b95d62e8329..e820c414b72 100644
--- a/reactos/ntoskrnl/mm/pagefile.c
+++ b/reactos/ntoskrnl/mm/pagefile.c
@@ -81,15 +81,15 @@ static ULONG MiPagingFileCount;
 ULONG MmNumberOfPagingFiles;
 
 /* Number of pages that are available for swapping */
-ULONG MiFreeSwapPages;
+PFN_NUMBER MiFreeSwapPages;
 
 /* Number of pages that have been allocated for swapping */
-ULONG MiUsedSwapPages;
+PFN_NUMBER MiUsedSwapPages;
 
 /*
  * Number of pages that have been reserved for swapping but not yet allocated
  */
-static ULONG MiReservedSwapPages;
+static PFN_NUMBER MiReservedSwapPages;
 
 /*
  * Ratio between reserved and available swap pages, e.g. setting this to five
diff --git a/reactos/ntoskrnl/mm/ppool.c b/reactos/ntoskrnl/mm/ppool.c
index 973736d759a..bfeb42ba6e2 100644
--- a/reactos/ntoskrnl/mm/ppool.c
+++ b/reactos/ntoskrnl/mm/ppool.c
@@ -159,8 +159,8 @@ typedef struct _R_POOL
 R_POOL, *PR_POOL;
 
 PVOID MmPagedPoolBase;
-ULONG MmPagedPoolSize;
-ULONG MmTotalPagedPoolQuota = 0; // TODO FIXME commented out until we use it
+SIZE_T MmPagedPoolSize;
+SIZE_T MmTotalPagedPoolQuota = 0; // TODO FIXME commented out until we use it
 static PR_POOL MmPagedPool = NULL;
 
 /* FUNCTIONS*******************************************************************/