diff --git a/arch/x86/paging.c b/arch/x86/paging.c
index 8b4ef08..666e0c3 100644
--- a/arch/x86/paging.c
+++ b/arch/x86/paging.c
@@ -25,20 +25,6 @@
 #define PD_SHIFT 22
 #define PD_MIRROR_PAGE_IDX 1023U
 
-/** Frontier between kernel and user space virtual addresses */
-#define PAGING_BASE_USER_ADDRESS (0x40000000) /* 1GB (must be 4MB-aligned) */
-#define PAGING_TOP_USER_ADDRESS  (0xFFFFFFFF) /* 4GB - 1B */
-#define PAGING_USER_SPACE_SIZE   (0xc0000000) /* 3GB */
-
-/** Length of the space reserved for the mirroring in the kernel
-    virtual space */
-#define PAGING_MIRROR_SIZE  (PAGE_SIZE << 10)  /* 1 PD = 1024 Page Tables = 4MB */
-
-/** Virtual address where the mirroring takes place */
-#define PAGING_MIRROR_VADDR \
-   (PAGING_BASE_USER_ADDRESS - PAGING_MIRROR_SIZE)
-
-
 static unsigned long mappedPage = 0;
 
 struct pde {
diff --git a/arch/x86/paging.h b/arch/x86/paging.h
index a862432..717a046 100644
--- a/arch/x86/paging.h
+++ b/arch/x86/paging.h
@@ -1,6 +1,19 @@
 #pragma once
 #include "types.h"
 
+/** Frontier between kernel and user space virtual addresses */
+#define PAGING_BASE_USER_ADDRESS (0x40000000) /* 1GB (must be 4MB-aligned) */
+#define PAGING_TOP_USER_ADDRESS  (0xFFFFFFFF) /* 4GB - 1B */
+#define PAGING_USER_SPACE_SIZE   (0xc0000000) /* 3GB */
+
+/** Length of the space reserved for the mirroring in the kernel
+    virtual space */
+#define PAGING_MIRROR_SIZE  (PAGE_SIZE << 10)  /* 1 PD = 1024 Page Tables = 4MB */
+
+/** Virtual address where the mirroring takes place */
+#define PAGING_MIRROR_VADDR \
+   (PAGING_BASE_USER_ADDRESS - PAGING_MIRROR_SIZE)
+
 #define PAGING_MEM_USER (1U << 0)
 #define PAGING_MEM_READ (1U << 1)
 #define PAGING_MEM_WRITE (1U << 2)
diff --git a/core/allocArea.c b/core/allocArea.c
index a30b60c..4c5bb20 100644
--- a/core/allocArea.c
+++ b/core/allocArea.c
@@ -33,8 +33,8 @@ void areaInit(vaddr_t firstMemUsed, vaddr_t lastUsed, vaddr_t stackBottom, vaddr
         int nbPagesStack = DIV_ROUND_UP((stackTop - stackBottom), PAGE_SIZE);
         areaAdd(ALIGN_DOWN(stackBottom, PAGE_SIZE), nbPagesStack, FALSE);
     }
-    //TODO: fix the 300 
-    areaAdd(ALIGN_DOWN(areaAddr + PAGE_SIZE, PAGE_SIZE), 300 , TRUE);
+    int nbFreePages = DIV_ROUND_UP((AREA_MEM_TOP - areaAddr), PAGE_SIZE);
+    areaAdd(ALIGN_DOWN(areaAddr + PAGE_SIZE, PAGE_SIZE), nbFreePages , TRUE);
     allocPopulate();
 }
 
diff --git a/core/allocArea.h b/core/allocArea.h
index 5a7618a..afa8674 100644
--- a/core/allocArea.h
+++ b/core/allocArea.h
@@ -6,6 +6,7 @@
 
 // areaAlloc map vmem to phy pages
 #define AREA_PHY_MAP (1<<0)
+#define AREA_MEM_TOP  PAGING_MIRROR_VADDR
 
 struct memArea {
     vaddr_t startAddr;