diff --git a/util/sis/jedec.c b/util/sis/jedec.c
index 73a399c43a..5947be18ac 100644
--- a/util/sis/jedec.c
+++ b/util/sis/jedec.c
@@ -29,7 +29,7 @@
 
 int probe_jedec (struct flashchip * flash)
 {
-	char * bios = flash->virt_addr;
+	char * volatile bios = flash->virt_addr;
 	unsigned char  id1, id2;
 
 	*(char *) (bios + 0x5555) = 0xAA;
@@ -55,7 +55,7 @@ int probe_jedec (struct flashchip * flash)
 
 int erase_jedec (struct flashchip * flash)
 {
-	char * bios = flash->virt_addr;
+	char * volatile bios = flash->virt_addr;
 
 	*(char *) (bios + 0x5555) = 0xAA;
 	*(char *) (bios + 0x2AAA) = 0x55;
diff --git a/util/sis/jedec.h b/util/sis/jedec.h
index de9c3d65c0..a2a86ff365 100644
--- a/util/sis/jedec.h
+++ b/util/sis/jedec.h
@@ -2,7 +2,7 @@ extern int probe_jedec (struct flashchip * flash);
 extern int erase_jedec (struct flashchip * flash);
 extern int write_jedec (struct flashchip * flash, char * buf);
 
-extern __inline__ void toggle_ready_jedec (char * dst)
+extern __inline__ void toggle_ready_jedec (char * volatile dst)
 {
 	unsigned int i = 0;
 	char tmp1, tmp2;
@@ -18,7 +18,7 @@ extern __inline__ void toggle_ready_jedec (char * dst)
 	}
 }
 
-extern __inline__ void data_polling_jedec (char * dst, char data)
+extern __inline__ void data_polling_jedec (char * volatile dst, char data)
 {
 	unsigned int i = 0;
 	char tmp;
@@ -33,7 +33,7 @@ extern __inline__ void data_polling_jedec (char * dst, char data)
 	}
 }
 
-extern __inline__ void protect_jedec (char * bios)
+extern __inline__ void protect_jedec (char * volatile bios)
 {
 	*(char *) (bios + 0x5555) = 0xAA;
 	*(char *) (bios + 0x2AAA) = 0x55;
@@ -42,7 +42,7 @@ extern __inline__ void protect_jedec (char * bios)
 	usleep(200);
 }
 
-extern __inline__ void write_page_jedec (char * bios, char * src, char * dst,
+extern __inline__ void write_page_jedec (char * volatile bios, char * volatile src, char * volatile dst,
 					 int page_size)
 {
 	int i;