diff --git a/lib/acpi/acpi_table.c b/lib/acpi/acpi_table.c
index 6473d95..150f750 100644
--- a/lib/acpi/acpi_table.c
+++ b/lib/acpi/acpi_table.c
@@ -420,7 +420,7 @@
 static int acpi_write_spcr(struct acpi_ctx *ctx, const struct acpi_writer *entry)
 {
 	struct serial_device_info serial_info = {0};
-	ulong serial_address, serial_offset;
+	u64 serial_address, serial_offset;
 	struct acpi_table_header *header;
 	struct acpi_spcr *spcr;
 	struct udevice *dev;
@@ -473,7 +473,7 @@
 	}
 
 	serial_width = serial_info.reg_width * 8;
-	serial_offset = serial_info.reg_offset << serial_info.reg_shift;
+	serial_offset = ((u64)serial_info.reg_offset) << serial_info.reg_shift;
 	serial_address = serial_info.addr + serial_offset;
 
 	/* Encode register access size */
@@ -495,7 +495,7 @@
 		break;
 	}
 
-	debug("UART type %u @ %lx\n", spcr->interface_type, serial_address);
+	debug("UART type %u @ %llx\n", spcr->interface_type, serial_address);
 
 	/* Fill GAS */
 	spcr->serial_port.space_id = space_id;