diff --git a/hw/isa/vt82c686.c b/hw/isa/vt82c686.c
index 223b947939..2f53bf8194 100644
--- a/hw/isa/vt82c686.c
+++ b/hw/isa/vt82c686.c
@@ -36,7 +36,7 @@
 
 typedef struct SuperIOConfig
 {
-    uint8_t config[0xff];
+    uint8_t config[0x100];
     uint8_t index;
     uint8_t data;
 } SuperIOConfig;