diff --git a/include/efi_api.h b/include/efi_api.h
index c98cc34..ebf2a3b 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -165,8 +165,9 @@ struct efi_boot_services {
 			void **handle, ...);
 	efi_status_t (EFIAPI *uninstall_multiple_protocol_interfaces)(
 			void *handle, ...);
-	efi_status_t (EFIAPI *calculate_crc32)(void *data,
-			unsigned long data_size, uint32_t *crc32);
+	efi_status_t (EFIAPI *calculate_crc32)(const void *data,
+					       efi_uintn_t data_size,
+					       u32 *crc32);
 	void (EFIAPI *copy_mem)(void *destination, const void *source,
 			size_t length);
 	void (EFIAPI *set_mem)(void *buffer, size_t size, uint8_t value);
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index c035425..820d766 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -2448,11 +2448,11 @@ static efi_status_t EFIAPI efi_uninstall_multiple_protocol_interfaces(
  *
  * Return: status code
  */
-static efi_status_t EFIAPI efi_calculate_crc32(void *data,
-					       unsigned long data_size,
-					       uint32_t *crc32_p)
+static efi_status_t EFIAPI efi_calculate_crc32(const void *data,
+					       efi_uintn_t data_size,
+					       u32 *crc32_p)
 {
-	EFI_ENTRY("%p, %ld", data, data_size);
+	EFI_ENTRY("%p, %zu", data, data_size);
 	*crc32_p = crc32(0, data, data_size);
 	return EFI_EXIT(EFI_SUCCESS);
 }