diff --git a/reactos/include/ddk/wdm.h b/reactos/include/ddk/wdm.h
index 2f0785c8df4..b7c9a63a563 100644
--- a/reactos/include/ddk/wdm.h
+++ b/reactos/include/ddk/wdm.h
@@ -1878,7 +1878,7 @@ typedef enum _EX_POOL_PRIORITY {
 #if !defined(_WIN64) && (defined(_NTDDK_) || defined(_NTIFS_) || defined(_NDIS_))
 #define LOOKASIDE_ALIGN
 #else
-#define LOOKASIDE_ALIGN /* FIXME: DECLSPEC_CACHEALIGN */
+#define LOOKASIDE_ALIGN DECLSPEC_CACHEALIGN
 #endif
 
 typedef struct _LOOKASIDE_LIST_EX *PLOOKASIDE_LIST_EX;
@@ -8333,7 +8333,7 @@ KeRestoreFloatingPointState(PVOID FloatingState)
 #define HIGH_LEVEL              15
 
 #define KI_USER_SHARED_DATA ((ULONG_PTR)(KADDRESS_BASE + 0xFFFE0000))
-extern volatile LARGE_INTEGER KeTickCount;
+extern DECLSPEC_CACHEALIGN volatile LARGE_INTEGER KeTickCount;
 
 #define PAUSE_PROCESSOR __yield();
 
diff --git a/reactos/include/psdk/ntdef.h b/reactos/include/psdk/ntdef.h
index 5f6a2583a32..d88b02b3dde 100644
--- a/reactos/include/psdk/ntdef.h
+++ b/reactos/include/psdk/ntdef.h
@@ -299,6 +299,18 @@
 #endif
 #endif /* DECLSPEC_ALIGN */
 
+#ifndef SYSTEM_CACHE_ALIGNMENT_SIZE
+#if defined(_AMD64_) || defined(_X86_)
+#define SYSTEM_CACHE_ALIGNMENT_SIZE 64
+#else
+#define SYSTEM_CACHE_ALIGNMENT_SIZE 128
+#endif
+#endif
+
+#ifndef DECLSPEC_CACHEALIGN
+#define DECLSPEC_CACHEALIGN DECLSPEC_ALIGN(SYSTEM_CACHE_ALIGNMENT_SIZE)
+#endif
+
 #ifndef DECLSPEC_SELECTANY
 #if (_MSC_VER >= 1100) || defined(__GNUC__)
 #define DECLSPEC_SELECTANY  __declspec(selectany)
diff --git a/reactos/include/xdk/extypes.h b/reactos/include/xdk/extypes.h
index 4d9bcb952c7..ae252d375ed 100644
--- a/reactos/include/xdk/extypes.h
+++ b/reactos/include/xdk/extypes.h
@@ -51,7 +51,7 @@ typedef enum _EX_POOL_PRIORITY {
 #if !defined(_WIN64) && (defined(_NTDDK_) || defined(_NTIFS_) || defined(_NDIS_))
 #define LOOKASIDE_ALIGN
 #else
-#define LOOKASIDE_ALIGN /* FIXME: DECLSPEC_CACHEALIGN */
+#define LOOKASIDE_ALIGN DECLSPEC_CACHEALIGN
 #endif
 
 typedef struct _LOOKASIDE_LIST_EX *PLOOKASIDE_LIST_EX;