diff --git a/include/dump/s390_dump.h b/include/dump/s390_dump.h
index 0865d78b..ad5ac1a8 100644
--- a/include/dump/s390_dump.h
+++ b/include/dump/s390_dump.h
@@ -26,6 +26,7 @@
 #define DF_S390_EM_STR		"DUMP_END"
 #define DF_S390_CPU_MAX		512
 #define DF_S390_MAGIC_BLK_ECKD	3
+#define DF_S390_DUMPER_MAGIC_SIZE	7
 #define DF_S390_DUMPER_MAGIC32		"ZECKD31"
 #define DF_S390_DUMPER_MAGIC64		"ZECKD64"
 #define DF_S390_DUMPER_MAGIC_EXT	"XECKD64"
diff --git a/zdump/df_s390.c b/zdump/df_s390.c
index 92dfa9c9..7177cddc 100644
--- a/zdump/df_s390.c
+++ b/zdump/df_s390.c
@@ -153,14 +153,17 @@ void df_s390_dumper_read(struct zg_fh *fh, int blk_size,
 		dumper->version = 0;
 	switch (dumper->version) {
 	case 1:
-		if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC_EXT, 7) == 0 ||
-		    strncmp(dumper->magic, DF_S390_DUMPER_MAGIC_MV_EXT, 7) == 0)
+		if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC_EXT,
+			    DF_S390_DUMPER_MAGIC_SIZE) == 0 ||
+		    strncmp(dumper->magic, DF_S390_DUMPER_MAGIC_MV_EXT,
+			    DF_S390_DUMPER_MAGIC_SIZE) == 0)
 			dumper->size = STAGE2_DUMPER_SIZE_V3;
 		else
 			dumper->size = STAGE2_DUMPER_SIZE_V1;
 		break;
 	case 2:
-		if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC_EXT, 7) == 0)
+		if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC_EXT,
+			    DF_S390_DUMPER_MAGIC_SIZE) == 0)
 			dumper->size = STAGE2_DUMPER_SIZE_ZLIB;
 		else
 			dumper->size = STAGE2_DUMPER_SIZE_V2;
diff --git a/zdump/dfi_s390mv.c b/zdump/dfi_s390mv.c
index 54a53f02..a6bcadf4 100644
--- a/zdump/dfi_s390mv.c
+++ b/zdump/dfi_s390mv.c
@@ -73,8 +73,8 @@ static struct {
 	struct df_s390_dumper	dumper;
 	int			dump_incomplete;
 	bool extended;
-	u64 magic_number;	/* Reference value to compare with */
-	char dumper_magic[7];	/* Reference value to compare with */
+	u64 magic_number;				/* Reference value to compare with */
+	char dumper_magic[DF_S390_DUMPER_MAGIC_SIZE];	/* Reference value to compare with */
 } l;
 
 /*
@@ -273,7 +273,7 @@ static void vol_init(struct vol *vol, struct vol_parm *vol_parm, int ssid,
 		l.dump_incomplete = 1;
 	}
 
-	if (strncmp(vol->dumper.magic, l.dumper_magic, 7) != 0) {
+	if (strncmp(vol->dumper.magic, l.dumper_magic, DF_S390_DUMPER_MAGIC_SIZE) != 0) {
 		vol->sign = SIGN_INVALID;
 		l.dump_incomplete = 1;
 	}
@@ -507,7 +507,7 @@ static int mv_dumper_read(void)
 		     ZG_CHECK_NONE) == -1)
 		return -ENODEV;
 	df_s390_dumper_read(g.fh, l.blk_size, &l.dumper);
-	if (strncmp(l.dumper.magic, l.dumper_magic, 7) != 0)
+	if (strncmp(l.dumper.magic, l.dumper_magic, DF_S390_DUMPER_MAGIC_SIZE) != 0)
 		return -ENODEV;
 	table_read(g.fh, l.blk_size, &l.table);
 	return 0;
@@ -567,10 +567,12 @@ static void set_magic_numbers(void)
 {
 	if (l.extended) {
 		l.magic_number = DF_S390_MAGIC_EXT;
-		memcpy(l.dumper_magic, DF_S390_DUMPER_MAGIC_MV_EXT, 7);
+		memcpy(l.dumper_magic, DF_S390_DUMPER_MAGIC_MV_EXT,
+		       DF_S390_DUMPER_MAGIC_SIZE);
 	} else {
 		l.magic_number = DF_S390_MAGIC;
-		memcpy(l.dumper_magic, DF_S390_DUMPER_MAGIC_MV, 7);
+		memcpy(l.dumper_magic, DF_S390_DUMPER_MAGIC_MV,
+		       DF_S390_DUMPER_MAGIC_SIZE);
 	}
 }
 
diff --git a/zdump/dt_s390sv.c b/zdump/dt_s390sv.c
index 7694700e..205480ea 100644
--- a/zdump/dt_s390sv.c
+++ b/zdump/dt_s390sv.c
@@ -34,14 +34,17 @@ static int dumper_read_eckd(int blk_size)
 	df_s390_dumper_read(g.fh, blk_size, &l.dumper);
 
 	if (l.extended) {
-		if (strncmp(l.dumper.magic, DF_S390_DUMPER_MAGIC_EXT, 7) != 0)
+		if (strncmp(l.dumper.magic, DF_S390_DUMPER_MAGIC_EXT,
+			    DF_S390_DUMPER_MAGIC_SIZE) != 0)
 			return -ENODEV;
 		l.dumper_arch = DFI_ARCH_64;
 		return 0;
 	}
-	if (strncmp(l.dumper.magic, DF_S390_DUMPER_MAGIC64, 7) == 0) {
+	if (strncmp(l.dumper.magic, DF_S390_DUMPER_MAGIC64,
+		    DF_S390_DUMPER_MAGIC_SIZE) == 0) {
 		l.dumper_arch = DFI_ARCH_64;
-	} else if (strncmp(l.dumper.magic, DF_S390_DUMPER_MAGIC32, 7) == 0) {
+	} else if (strncmp(l.dumper.magic, DF_S390_DUMPER_MAGIC32,
+			   DF_S390_DUMPER_MAGIC_SIZE) == 0) {
 		l.dumper_arch = DFI_ARCH_32;
 	} else if (memcmp(l.dumper.magic, OLD_DUMPER_HEX_INSTR1, 4) == 0 &&
 		   l.dumper.version == 0) {
@@ -59,15 +62,17 @@ static int dumper_read_eckd(int blk_size)
 static int dumper_check_fba(struct df_s390_dumper *dumper)
 {
 	if (l.extended) {
-		if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC_FBA_EXT, 7)
-		    != 0)
+		if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC_FBA_EXT,
+			    DF_S390_DUMPER_MAGIC_SIZE) != 0)
 			return -ENODEV;
 		l.dumper_arch = DFI_ARCH_64;
 		return 0;
 	}
-	if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC64_FBA, 7) == 0) {
+	if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC64_FBA,
+		    DF_S390_DUMPER_MAGIC_SIZE) == 0) {
 		l.dumper_arch = DFI_ARCH_64;
-	} else if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC32_FBA, 7) == 0) {
+	} else if (strncmp(dumper->magic, DF_S390_DUMPER_MAGIC32_FBA,
+			   DF_S390_DUMPER_MAGIC_SIZE) == 0) {
 		l.dumper_arch = DFI_ARCH_32;
 	} else if (memcmp(dumper->magic, OLD_DUMPER_HEX_INSTR1, 4) == 0 &&
 		   memcmp(&dumper->size, OLD_DUMPER_HEX_INSTR2, 2) == 0) {