diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 3f7777b255aa..91abf5b2fb94 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -143,7 +143,7 @@ void __init e820_print_map(char *who)
  *
  */
 int __init sanitize_e820_map(struct e820entry *biosmap, int max_nr_map,
-				char *pnr_map)
+				int *pnr_map)
 {
 	struct change_member {
 		struct e820entry *pbios; /* pointer to original bios entry */
@@ -204,6 +204,7 @@ static struct e820entry new_bios[E820_X_MAX] __initdata;
 		return -1;
 
 	old_nr = *pnr_map;
+	BUG_ON(old_nr > max_nr_map);
 
 	/* bail out if we find any unreasonable addresses in bios map */
 	for (i = 0; i < old_nr; i++)
@@ -401,7 +402,7 @@ u64 __init update_memory_range(u64 start, u64 size, unsigned old_type,
 
 void __init update_e820(void)
 {
-	u8 nr_map;
+	int nr_map;
 
 	nr_map = e820.nr_map;
 	if (sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &nr_map))
diff --git a/arch/x86/kernel/e820_64.c b/arch/x86/kernel/e820_64.c
index 58dc6eee4d4f..354fbb221709 100644
--- a/arch/x86/kernel/e820_64.c
+++ b/arch/x86/kernel/e820_64.c
@@ -407,15 +407,18 @@ static void early_panic(char *msg)
 char *__init machine_specific_memory_setup(void)
 {
 	char *who = "BIOS-e820";
+	int new_nr;
 	/*
 	 * Try to copy the BIOS-supplied E820-map.
 	 *
 	 * Otherwise fake a memory map; one section from 0k->640k,
 	 * the next section from 1mb->appropriate_mem_k
 	 */
+	new_nr = boot_params.e820_entries;
 	sanitize_e820_map(boot_params.e820_map,
 			ARRAY_SIZE(boot_params.e820_map),
-			&boot_params.e820_entries);
+			&new_nr);
+	boot_params.e820_entries = new_nr;
 	if (copy_e820_map(boot_params.e820_map, boot_params.e820_entries) < 0)
 		early_panic("Cannot find a valid memory map");
 	printk(KERN_INFO "BIOS-provided physical RAM map:\n");
@@ -484,7 +487,7 @@ early_param("memmap", parse_memmap_opt);
 void __init finish_e820_parsing(void)
 {
 	if (userdef) {
-		char nr = e820.nr_map;
+		int nr = e820.nr_map;
 
 		if (sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &nr) < 0)
 			early_panic("Invalid user supplied memory map");
diff --git a/arch/x86/mach-default/setup.c b/arch/x86/mach-default/setup.c
index 38a856c4fc07..56b4c39cb7fa 100644
--- a/arch/x86/mach-default/setup.c
+++ b/arch/x86/mach-default/setup.c
@@ -153,6 +153,7 @@ late_initcall(print_ipi_mode);
 char * __init machine_specific_memory_setup(void)
 {
 	char *who;
+	int new_nr;
 
 
 	who = "BIOS-e820";
@@ -163,9 +164,11 @@ char * __init machine_specific_memory_setup(void)
 	 * Otherwise fake a memory map; one section from 0k->640k,
 	 * the next section from 1mb->appropriate_mem_k
 	 */
+	new_nr = boot_params.e820_entries;
 	sanitize_e820_map(boot_params.e820_map,
 			ARRAY_SIZE(boot_params.e820_map),
-			&boot_params.e820_entries);
+			&new_nr);
+	boot_params.e820_entries = new_nr;
 	if (copy_e820_map(boot_params.e820_map, boot_params.e820_entries)
 	    < 0) {
 		unsigned long mem_size;
diff --git a/arch/x86/mach-voyager/setup.c b/arch/x86/mach-voyager/setup.c
index 662b5c0a77d6..f4aca9fa9546 100644
--- a/arch/x86/mach-voyager/setup.c
+++ b/arch/x86/mach-voyager/setup.c
@@ -62,6 +62,7 @@ void __init time_init_hook(void)
 char *__init machine_specific_memory_setup(void)
 {
 	char *who;
+	int new_nr;
 
 	who = "NOT VOYAGER";
 
@@ -111,9 +112,11 @@ char *__init machine_specific_memory_setup(void)
 	 * Otherwise fake a memory map; one section from 0k->640k,
 	 * the next section from 1mb->appropriate_mem_k
 	 */
+	new_nr = boot_params.e820_entries;
 	sanitize_e820_map(boot_params.e820_map,
 			ARRAY_SIZE(boot_params.e820_map),
-			&boot_params.e820_entries);
+			&new_nr);
+	boot_params.e820_entries = new_nr;
 	if (copy_e820_map(boot_params.e820_map, boot_params.e820_entries)
 	    < 0) {
 		unsigned long mem_size;
diff --git a/include/asm-x86/e820.h b/include/asm-x86/e820.h
index ab18457a95c0..1eb13b881437 100644
--- a/include/asm-x86/e820.h
+++ b/include/asm-x86/e820.h
@@ -63,7 +63,7 @@ extern int e820_all_mapped(u64 start, u64 end, unsigned type);
 extern void add_memory_region(u64 start, u64 size, int type);
 extern void e820_print_map(char *who);
 extern int
-sanitize_e820_map(struct e820entry *biosmap, int max_nr_map, char *pnr_map);
+sanitize_e820_map(struct e820entry *biosmap, int max_nr_map, int *pnr_map);
 extern int copy_e820_map(struct e820entry *biosmap, int nr_map);
 extern u64 update_memory_range(u64 start, u64 size, unsigned old_type,
 			       unsigned new_type);