diff --git a/ntoskrnl/mm/ARM3/mminit.c b/ntoskrnl/mm/ARM3/mminit.c
index 5e4bc303e01..f1d7c2b7e95 100644
--- a/ntoskrnl/mm/ARM3/mminit.c
+++ b/ntoskrnl/mm/ARM3/mminit.c
@@ -242,7 +242,7 @@ PMMPTE MiHighestUserPxe;
 /* These variables define the system cache address space */
 PVOID MmSystemCacheStart = (PVOID)MI_SYSTEM_CACHE_START;
 PVOID MmSystemCacheEnd;
-ULONG MmSizeOfSystemCacheInPages;
+ULONG_PTR MmSizeOfSystemCacheInPages;
 MMSUPPORT MmSystemCacheWs;
 
 //