diff --git a/xtoskrnl/mm/pfn.cc b/xtoskrnl/mm/pfn.cc
index ad94f0c..e88ee22 100644
--- a/xtoskrnl/mm/pfn.cc
+++ b/xtoskrnl/mm/pfn.cc
@@ -1146,6 +1146,10 @@ MM::Pfn::ScanMemoryDescriptors(VOID)
     PLOADER_MEMORY_DESCRIPTOR MemoryDescriptor;
     PFN_NUMBER FreePages;
 
+    /* Initialize the lowest and highest physical page numbers */
+    LowestPhysicalPage = ~0;
+    HighestPhysicalPage = 0;
+
     /* Initially, set number of free pages to 0 */
     FreePages = 0;