diff --git a/arch/arm/include/arch/types.h b/arch/arm/include/arch/types.h
index 72e875c..b8b7c51 100644
--- a/arch/arm/include/arch/types.h
+++ b/arch/arm/include/arch/types.h
@@ -19,3 +19,5 @@
  */
 
 #include <arch-generic/types.h>
+
+#define arch_uint_ptr uint32
diff --git a/include/arch-generic/types.h b/include/arch-generic/types.h
index 8dd868a..3e22143 100644
--- a/include/arch-generic/types.h
+++ b/include/arch-generic/types.h
@@ -18,4 +18,5 @@
     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-typedef unsigned int uint32;
+typedef unsigned long uint32;
+typedef unsigned long long uint64;
diff --git a/include/atags.h b/include/atags.h
index 684a90f..f1b78e0 100644
--- a/include/atags.h
+++ b/include/atags.h
@@ -42,7 +42,7 @@ struct atag_core {
 
 struct atag_mem {
 	uint32 size;	/* size of the area */
-	uint32 start;	/* physical start address */
+	arch_uint_ptr start;	/* physical start address */
 };
 
 struct atag {
diff --git a/kernel/atags.c b/kernel/atags.c
index 6c86ddd..d724c2a 100644
--- a/kernel/atags.c
+++ b/kernel/atags.c
@@ -20,7 +20,7 @@
 
 #include <atags.h>
 
-extern uint32 atags_ptr;
+extern arch_uint_ptr atags_ptr;
 
 int atag_valid(struct atag *a) {
 	switch (a->tag) {
diff --git a/kernel/mm.c b/kernel/mm.c
index 0a5f629..db9659f 100644
--- a/kernel/mm.c
+++ b/kernel/mm.c
@@ -21,6 +21,7 @@
 #include <list.h>
 #include <mm.h>
 #include <print.h>
+#include <types.h>
 
 struct dlist_node mm_free_page_list;
 
@@ -56,13 +57,13 @@ void mm_add_free_region(void *start, void *end) {
 		start = (char *)start + MM_PAGE_SIZE;
 
 	//make sure both start and end address are aligned to the size of a page
-	if ((unsigned int)start % MM_PAGE_SIZE != 0)
-		start = (char*)start + (MM_PAGE_SIZE - ((unsigned int)start % MM_PAGE_SIZE));
-	if (((unsigned int)end + 1) % MM_PAGE_SIZE != 0)
-		end = (char*)end - ((unsigned int)end + 1) % MM_PAGE_SIZE;
+	if ((arch_uint_ptr)start % MM_PAGE_SIZE != 0)
+		start = (char*)start + (MM_PAGE_SIZE - ((arch_uint_ptr)start % MM_PAGE_SIZE));
+	if (((arch_uint_ptr)end + 1) % MM_PAGE_SIZE != 0)
+		end = (char*)end - ((arch_uint_ptr)end + 1) % MM_PAGE_SIZE;
 
 	if ((char *)end + 1 - (char *)start < MM_PAGE_SIZE<<1) {
-		print("Error: Supplied memory area(%x,%x) is smaller than the page size (%d)\n", (unsigned int)start, (unsigned int)end, MM_PAGE_SIZE);
+		print("Error: Supplied memory area(%x,%x) is smaller than the page size (%d)\n", (arch_uint_ptr)start, (arch_uint_ptr)end, MM_PAGE_SIZE);
 		return;
 	}