diff --git a/reactos/ntoskrnl/include/internal/mm.h b/reactos/ntoskrnl/include/internal/mm.h
index b102d943f8f..39686a1dc24 100644
--- a/reactos/ntoskrnl/include/internal/mm.h
+++ b/reactos/ntoskrnl/include/internal/mm.h
@@ -986,6 +986,9 @@ MiGetPfnEntry(IN PFN_TYPE Pfn)
     extern PPHYSICAL_PAGE MmPageArray;
     extern ULONG MmPageArraySize;
 
+    /* Mark MmPageArraySize as unreferenced, otherwise it will appear as an unused variable on a Release build */
+    UNREFERENCED_PARAMETER(MmPageArraySize);
+
     /* Make sure the PFN number is valid */
     ASSERT(Pfn <= MmPageArraySize);