diff --git a/kernel/memory/pageframealloc.cc b/kernel/memory/pageframealloc.cc
index f47ab60..ff3ed50 100644
--- a/kernel/memory/pageframealloc.cc
+++ b/kernel/memory/pageframealloc.cc
@@ -29,11 +29,18 @@ void PageFrameAllocator::init(){
         memory_map_entry = memory_map_entry->getNext();
     }
 
+    // kernel image
     for(uint64_t i = (uint64_t)&___KERNEL_START___; i < (uint64_t)&___KERNEL_END___; i += 4096){
         uint64_t pg = i/4096;
         bitmap[pg/8] &= ~(1 << pg%8);
     }
 
+    // ISA adresses
+    for(uint64_t i = (uint64_t)0x00F00000; i < (uint64_t)0x00FFFFFF; i += 4096){
+        uint64_t pg = i/4096;
+        bitmap[pg/8] &= ~(1 << pg%8);
+    }
+
     stats();
 }