diff --git a/src/mm.c b/src/mm.c
index f794801..d33be73 100644
--- a/src/mm.c
+++ b/src/mm.c
@@ -1,15 +1,15 @@
 #include "mm.h"
 
-#define PAGE_SIZE 4096u
-
 typedef struct mm_page_entry_s {
     size_t count;
     struct mm_page_entry_s * next;
 } mm_region_entry_t;
 
 static mm_region_entry_t * mm_next_free_region;
-static size_t mm_free_page_count;
+static size_t mm_free_pages;
 static size_t mm_total_ram;
+static size_t kernel_start_address;
+static size_t kernel_size;
 
 extern uint8_t _hos_mem_start;
 extern uint8_t _hos_mem_end;
@@ -22,12 +22,11 @@ static void mm_add_ram_region(size_t base, size_t size)
     region->next = mm_next_free_region;
     mm_next_free_region = region;
     mm_total_ram += size;
-    mm_free_page_count = pages;
+    mm_free_pages = pages;
 }
 
 void mm_register_ram_region(uint64_t base, size_t size)
 {
-    size &= ~(PAGE_SIZE - 1u);
     /* Ignore any RAM region above 4GB. */
     if (base >= 0x100000000ull)
     {
@@ -37,34 +36,43 @@ void mm_register_ram_region(uint64_t base, size_t size)
     {
         size = (size_t)(0x100000000ull - base);
     }
+    size_t end_address = mm_page_floor((size_t)base + size);
+    size_t start_address = mm_page_ceil(base);
+    size = end_address - start_address;
+    if (size < PAGE_SIZE)
+    {
+        return;
+    }
+    size_t kernel_end_address = kernel_start_address + kernel_size;
     /* Add regions before and after kernel RAM. */
-    size_t region_base = (size_t)base;
-    if (region_base < (size_t)&_hos_mem_start)
+    if (start_address < kernel_start_address)
     {
         /* RAM region begins before kernel RAM. */
         size_t this_sz = size;
-        if ((region_base + this_sz) > (size_t)&_hos_mem_start)
+        if ((start_address + this_sz) > kernel_start_address)
         {
-            this_sz = (size_t)&_hos_mem_start - region_base;
+            this_sz = kernel_start_address - start_address;
         }
-        mm_add_ram_region(region_base, this_sz);
+        mm_add_ram_region(start_address, this_sz);
     }
-    if ((region_base + size) > (size_t)&_hos_mem_end)
+    if ((start_address + size) > kernel_end_address)
     {
         /* RAM region ends after kernel RAM. */
         size_t this_sz = size;
-        if (region_base < (size_t)&_hos_mem_end)
+        if (start_address < kernel_end_address)
         {
-            this_sz = (region_base + size) - (size_t)&_hos_mem_end;
-            region_base = (size_t)&_hos_mem_end;
+            this_sz = (start_address + size) - kernel_end_address;
+            start_address = kernel_end_address;
         }
-        mm_add_ram_region(region_base, this_sz);
+        mm_add_ram_region(start_address, this_sz);
     }
 }
 
 void mm_init(void)
 {
-    mm_total_ram = mm_get_kernel_size();;
+    kernel_start_address = mm_page_floor((size_t)&_hos_mem_start);
+    kernel_size = mm_page_ceil((size_t)&_hos_mem_end - kernel_start_address);
+    mm_total_ram = kernel_size;
 }
 
 size_t mm_get_total_ram(void)
@@ -74,10 +82,10 @@ size_t mm_get_total_ram(void)
 
 size_t mm_get_kernel_address(void)
 {
-    return (size_t)&_hos_mem_start;
+    return kernel_start_address;
 }
 
 size_t mm_get_kernel_size(void)
 {
-    return &_hos_mem_end - &_hos_mem_start;
+    return kernel_size;
 }
diff --git a/src/mm.h b/src/mm.h
index 9ac0665..f195412 100644
--- a/src/mm.h
+++ b/src/mm.h
@@ -4,6 +4,18 @@
 #include <stdint.h>
 #include <stddef.h>
 
+#define PAGE_SIZE 4096u
+
+static inline size_t mm_page_floor(size_t bytes)
+{
+    return bytes & ~(PAGE_SIZE - 1u);
+}
+
+static inline size_t mm_page_ceil(size_t bytes)
+{
+    return (bytes + PAGE_SIZE - 1u) & ~(PAGE_SIZE - 1u);
+}
+
 void mm_init(void);
 void mm_register_ram_region(uint64_t base, size_t size);
 size_t mm_get_total_ram(void);