diff --git a/arch/s390/boot/alternative.c b/arch/s390/boot/alternative.c
index 19ea7934b918..77e8bad560c5 100644
--- a/arch/s390/boot/alternative.c
+++ b/arch/s390/boot/alternative.c
@@ -45,11 +45,12 @@ static void alt_debug_modify(int type, unsigned int nr, bool clear)
 
 static char *alt_debug_parse(int type, char *str)
 {
-	unsigned long val, endval;
+	unsigned long val, endval, limit;
 	char *endp;
 	bool clear;
 	int i;
 
+	limit = type == ALT_TYPE_FACILITY ? MAX_FACILITY_BIT : MAX_MFEATURE_BIT;
 	if (*str == ':') {
 		str++;
 	} else {
@@ -73,7 +74,7 @@ static char *alt_debug_parse(int type, char *str)
 			if (str == endp)
 				break;
 			str = endp;
-			while (val <= endval) {
+			while (val <= endval && val < limit) {
 				alt_debug_modify(type, val, clear);
 				val++;
 			}
diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c
index 59eabf4a2de0..c1b43e5e688a 100644
--- a/arch/s390/boot/ipl_parm.c
+++ b/arch/s390/boot/ipl_parm.c
@@ -230,7 +230,7 @@ static void modify_fac_list(char *str)
 			if (str == endp)
 				break;
 			str = endp;
-			while (val <= endval) {
+			while (val <= endval && val < MAX_FACILITY_BIT) {
 				modify_facility(val, clear);
 				val++;
 			}