diff --git a/zipl/boot/stage3.c b/zipl/boot/stage3.c
index 8719155a..fe8f358a 100644
--- a/zipl/boot/stage3.c
+++ b/zipl/boot/stage3.c
@@ -292,7 +292,7 @@ void start(void)
 	/* store subchannel ID into low core and into new kernel space */
 	subchannel_id = S390_lowcore.subchannel_id;
 	*(unsigned int *)__LC_IPLDEV = subchannel_id;
-	*(unsigned int *)IPL_DEVICE = subchannel_id;
+	*(unsigned long long *)IPL_DEVICE = subchannel_id;
 
 	/* if valid command line is given, copy it into new kernel space */
 	if (_parm_addr != UNSPECIFIED_ADDRESS) {
diff --git a/zipl/boot/stage3.h b/zipl/boot/stage3.h
index 8db17e32..a4a3d7c8 100644
--- a/zipl/boot/stage3.h
+++ b/zipl/boot/stage3.h
@@ -17,7 +17,7 @@
 
 #include "boot/ipl.h"
 
-#define IPL_DEVICE		 0x10404UL
+#define IPL_DEVICE		 0x10400UL
 #define INITRD_START		 0x10408UL
 #define INITRD_SIZE		 0x10410UL
 #define OLDMEM_BASE		 0x10418UL