diff --git a/pc-bios/s390-ccw/sclp.c b/pc-bios/s390-ccw/sclp.c
index c0223fab0b..7251f9af4d 100644
--- a/pc-bios/s390-ccw/sclp.c
+++ b/pc-bios/s390-ccw/sclp.c
@@ -112,7 +112,7 @@ void sclp_get_loadparm_ascii(char *loadparm)
     ReadInfo *sccb = (void *)_sccb;
 
     memset((char *)_sccb, 0, sizeof(ReadInfo));
-    sccb->h.length = sizeof(ReadInfo);
+    sccb->h.length = SCCB_SIZE;
     if (!sclp_service_call(SCLP_CMDW_READ_SCP_INFO, sccb)) {
         ebcdic_to_ascii((char *) sccb->loadparm, loadparm, LOADPARM_LEN);
     }