diff --git a/ntoskrnl/include/internal/mm.h b/ntoskrnl/include/internal/mm.h
index 91bf7599df236..1c3870d6370a6 100644
--- a/ntoskrnl/include/internal/mm.h
+++ b/ntoskrnl/include/internal/mm.h
@@ -131,6 +131,13 @@ typedef ULONG_PTR SWAPENTRY;
 #define MM_ROUND_DOWN(x,s)                  \
     ((PVOID)(((ULONG_PTR)(x)) & ~((ULONG_PTR)(s)-1)))
 
+/* PAGE_ROUND_UP and PAGE_ROUND_DOWN equivalent, with support for 64-bit-only data types */
+#define PAGE_ROUND_UP_64(x) \
+    (((x) + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1))
+
+#define PAGE_ROUND_DOWN_64(x) \
+    ((x) & ~(PAGE_SIZE - 1))
+
 #define PAGE_FLAGS_VALID_FOR_SECTION \
     (PAGE_READONLY | \
      PAGE_READWRITE | \
diff --git a/ntoskrnl/mm/section.c b/ntoskrnl/mm/section.c
index 73b414315fe38..d570dbc3cec0f 100644
--- a/ntoskrnl/mm/section.c
+++ b/ntoskrnl/mm/section.c
@@ -4876,7 +4876,7 @@ MmPurgeSegment(
     }
 
     /* Find byte offset of the page to start */
-    PurgeStart.QuadPart = PAGE_ROUND_DOWN(PurgeStart.QuadPart);
+    PurgeStart.QuadPart = PAGE_ROUND_DOWN_64(PurgeStart.QuadPart);
 
     while (PurgeStart.QuadPart < PurgeEnd.QuadPart)
     {
@@ -4947,7 +4947,7 @@ MmIsDataSectionResident(
         return FALSE;
 
     /* Find byte offset of the page to start */
-    RangeStart.QuadPart = PAGE_ROUND_DOWN(RangeStart.QuadPart);
+    RangeStart.QuadPart = PAGE_ROUND_DOWN_64(RangeStart.QuadPart);
 
     MmLockSectionSegment(Segment);
 
@@ -5010,7 +5010,7 @@ MmMakeSegmentDirty(
         return STATUS_NOT_MAPPED_VIEW;
 
     /* Find byte offset of the page to start */
-    RangeStart.QuadPart = PAGE_ROUND_DOWN(RangeStart.QuadPart);
+    RangeStart.QuadPart = PAGE_ROUND_DOWN_64(RangeStart.QuadPart);
 
     MmLockSectionSegment(Segment);
 
@@ -5098,7 +5098,7 @@ MmFlushSegment(
     }
 
     /* Find byte offset of the page to start */
-    FlushStart.QuadPart = PAGE_ROUND_DOWN(FlushStart.QuadPart);
+    FlushStart.QuadPart = PAGE_ROUND_DOWN_64(FlushStart.QuadPart);
 
     while (FlushStart.QuadPart < FlushEnd.QuadPart)
     {