diff --git a/kernel/busses/i2c-piix4.c b/kernel/busses/i2c-piix4.c
index feed5b99..698353d9 100644
--- a/kernel/busses/i2c-piix4.c
+++ b/kernel/busses/i2c-piix4.c
@@ -186,14 +186,16 @@ static unsigned short piix4_smba = 0;
 /*
  * Get DMI information.
  */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,99)
 void dmi_scan_machine(void);
-#define IBM_SIGNATURE		"IBM"
+#endif
 static int __init ibm_dmi_probe(void)
 {
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,99)
 	extern int is_unsafe_smbus;
 	return is_unsafe_smbus;
 #else
+#define IBM_SIGNATURE		"IBM"
 	dmi_scan_machine();
 	if(dmi_ident[DMI_SYS_VENDOR] == NULL)
 		return 0;