diff --git a/hw/pc.c b/hw/pc.c
index 905d401e21..69f25f39aa 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -54,9 +54,6 @@
 
 #define MAX_IDE_BUS 2
 
-extern uint8_t *acpi_tables;
-extern size_t acpi_tables_len;
-
 static fdctrl_t *floppy_controller;
 static RTCState *rtc_state;
 static PITState *pit;
@@ -443,7 +440,8 @@ static void bochs_bios_init(void)
     fw_cfg = fw_cfg_init(BIOS_CFG_IOPORT, BIOS_CFG_IOPORT + 1, 0, 0);
     fw_cfg_add_i32(fw_cfg, FW_CFG_ID, 1);
     fw_cfg_add_i64(fw_cfg, FW_CFG_RAM_SIZE, (uint64_t)ram_size);
-    fw_cfg_add_bytes(fw_cfg, FW_CFG_ACPI_TABLES, acpi_tables, acpi_tables_len);
+    fw_cfg_add_bytes(fw_cfg, FW_CFG_ACPI_TABLES, (uint8_t *)acpi_tables,
+                     acpi_tables_len);
 }
 
 /* Generate an initial boot sector which sets state and jump to
diff --git a/hw/pc.h b/hw/pc.h
index 7da0c3fb50..3089e788ac 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -101,6 +101,9 @@ int ioport_get_a20(void);
 
 /* acpi.c */
 extern int acpi_enabled;
+extern char *acpi_tables;
+extern size_t acpi_tables_len;
+
 i2c_bus *piix4_pm_init(PCIBus *bus, int devfn, uint32_t smb_io_base,
                        qemu_irq sci_irq);
 void piix4_smbus_register_device(SMBusDevice *dev, uint8_t addr);