diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
index 17cf96c45f2b..1815849f83cb 100644
--- a/drivers/firmware/memmap.c
+++ b/drivers/firmware/memmap.c
@@ -286,7 +286,7 @@ int __meminit firmware_map_add_hotplug(u64 start, u64 end, const char *type)
 {
 	struct firmware_map_entry *entry;
 
-	entry = firmware_map_find_entry_bootmem(start, end, type);
+	entry = firmware_map_find_entry_bootmem(start, end - 1, type);
 	if (!entry) {
 		entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
 		if (!entry)