diff --git a/pc-bios/s390-ccw/iplb.h b/pc-bios/s390-ccw/iplb.h
index ded20c834e11..772d5c57c94e 100644
--- a/pc-bios/s390-ccw/iplb.h
+++ b/pc-bios/s390-ccw/iplb.h
@@ -12,6 +12,8 @@
 #ifndef IPLB_H
 #define IPLB_H
 
+#define LOADPARM_LEN    8
+
 struct IplBlockCcw {
     uint8_t  reserved0[85];
     uint8_t  ssid;
@@ -61,7 +63,7 @@ struct IplParameterBlock {
     uint8_t  pbt;
     uint8_t  flags;
     uint16_t reserved01;
-    uint8_t  loadparm[8];
+    uint8_t  loadparm[LOADPARM_LEN];
     union {
         IplBlockCcw ccw;
         IplBlockFcp fcp;
diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
index 26f9adf84a31..544851d672d8 100644
--- a/pc-bios/s390-ccw/main.c
+++ b/pc-bios/s390-ccw/main.c
@@ -15,7 +15,7 @@
 char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
 static SubChannelId blk_schid = { .one = 1 };
 IplParameterBlock iplb __attribute__((__aligned__(PAGE_SIZE)));
-static char loadparm_str[9] = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+static char loadparm_str[LOADPARM_LEN + 1] = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 QemuIplParameters qipl;
 
 #define LOADPARM_PROMPT "PROMPT  "
@@ -80,13 +80,13 @@ static bool find_dev(Schib *schib, int dev_no)
 
 static void menu_setup(void)
 {
-    if (memcmp(loadparm_str, LOADPARM_PROMPT, 8) == 0) {
+    if (memcmp(loadparm_str, LOADPARM_PROMPT, LOADPARM_LEN) == 0) {
         menu_set_parms(QIPL_FLAG_BM_OPTS_CMD, 0);
         return;
     }
 
     /* If loadparm was set to any other value, then do not enable menu */
-    if (memcmp(loadparm_str, LOADPARM_EMPTY, 8) != 0) {
+    if (memcmp(loadparm_str, LOADPARM_EMPTY, LOADPARM_LEN) != 0) {
         return;
     }
 
@@ -117,7 +117,7 @@ static void virtio_setup(void)
     enable_mss_facility();
 
     sclp_get_loadparm_ascii(loadparm_str);
-    memcpy(ldp + 10, loadparm_str, 8);
+    memcpy(ldp + 10, loadparm_str, LOADPARM_LEN);
     sclp_print(ldp);
 
     memcpy(&qipl, early_qipl, sizeof(QemuIplParameters));
diff --git a/pc-bios/s390-ccw/sclp.c b/pc-bios/s390-ccw/sclp.c
index 3836cb4716bd..c0223fab0bea 100644
--- a/pc-bios/s390-ccw/sclp.c
+++ b/pc-bios/s390-ccw/sclp.c
@@ -114,7 +114,7 @@ void sclp_get_loadparm_ascii(char *loadparm)
     memset((char *)_sccb, 0, sizeof(ReadInfo));
     sccb->h.length = sizeof(ReadInfo);
     if (!sclp_service_call(SCLP_CMDW_READ_SCP_INFO, sccb)) {
-        ebcdic_to_ascii((char *) sccb->loadparm, loadparm, 8);
+        ebcdic_to_ascii((char *) sccb->loadparm, loadparm, LOADPARM_LEN);
     }
 }
 
diff --git a/pc-bios/s390-ccw/sclp.h b/pc-bios/s390-ccw/sclp.h
index 0dd987ff5dc4..8450161ba7a2 100644
--- a/pc-bios/s390-ccw/sclp.h
+++ b/pc-bios/s390-ccw/sclp.h
@@ -56,7 +56,7 @@ typedef struct ReadInfo {
     uint16_t rnmax;
     uint8_t rnsize;
     uint8_t reserved[13];
-    uint8_t loadparm[8];
+    uint8_t loadparm[LOADPARM_LEN];
 } __attribute__((packed)) ReadInfo;
 
 typedef struct SCCB {