diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2c2e9dcbf4..82a7daa188 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -75,7 +75,7 @@
 /* Leave a chunk of memory at the top of RAM for the BIOS ACPI tables
  * (128K) and other BIOS datastructures (less than 4K reported to be used at
  * the moment, 32K should be enough for a while).  */
-unsigned acpi_data_size = 0x20000 + 0x8000;
+static unsigned acpi_data_size = 0x20000 + 0x8000;
 void pc_set_legacy_acpi_data_size(void)
 {
     acpi_data_size = 0x10000;