diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
index 1f6b817..307d5d7 100644
--- a/lib/efi_loader/efi_disk.c
+++ b/lib/efi_loader/efi_disk.c
@@ -148,7 +148,7 @@
 	    (uintptr_t)buffer & (this->media->io_align - 1))
 		return EFI_INVALID_PARAMETER;
 	if (lba * this->media->block_size + buffer_size >
-	    this->media->last_block * this->media->block_size)
+	    (this->media->last_block + 1) * this->media->block_size)
 		return EFI_INVALID_PARAMETER;
 
 #ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER
@@ -216,7 +216,7 @@
 	    (uintptr_t)buffer & (this->media->io_align - 1))
 		return EFI_INVALID_PARAMETER;
 	if (lba * this->media->block_size + buffer_size >
-	    this->media->last_block * this->media->block_size)
+	    (this->media->last_block + 1) * this->media->block_size)
 		return EFI_INVALID_PARAMETER;
 
 #ifdef CONFIG_EFI_LOADER_BOUNCE_BUFFER