diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index c94bcc5398..790401f91b 100644
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -18985,6 +18985,8 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 	unsigned char algorithms[256];
 	unsigned int i;
 
+	enum { notexpected = 0, expected = 1, found = 2 };
+
 	REQUIRE(DNS_ZONE_VALID(zone));
 
 	result = dns_db_getoriginnode(db, &node);
@@ -19036,7 +19038,7 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 	 */
 	if (dns_rdataset_isassociated(&cds)) {
 		bool delete = false;
-		memset(algorithms, 0, sizeof(algorithms));
+		memset(algorithms, notexpected, sizeof(algorithms));
 		for (result = dns_rdataset_first(&cds);
 		     result == ISC_R_SUCCESS;
 		     result = dns_rdataset_next(&cds)) {
@@ -19056,7 +19058,7 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 			}
 			CHECK(dns_rdata_tostruct(&crdata, &structcds, NULL));
 			if (algorithms[structcds.algorithm] == 0) {
-				algorithms[structcds.algorithm] = 1;
+				algorithms[structcds.algorithm] = expected;
 			}
 			for (result = dns_rdataset_first(&dnskey);
 			     result == ISC_R_SUCCESS;
@@ -19072,7 +19074,7 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 				    memcmp(crdata.data, dsrdata.data,
 					   dsrdata.length) == 0)
 				{
-					algorithms[structcds.algorithm] = 2;
+					algorithms[structcds.algorithm] = found;
 				}
 			}
 			if (result != ISC_R_NOMORE) {
@@ -19081,11 +19083,11 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 		}
 		for (i = 0; i < sizeof(algorithms); i++) {
 			if (delete) {
-				if (algorithms[i] != 0) {
+				if (algorithms[i] != notexpected) {
 					result = DNS_R_BADCDS;
 					goto failure;
 				}
-			} else if (algorithms[i] == 1) {
+			} else if (algorithms[i] == expected) {
 				result = DNS_R_BADCDS;
 				goto failure;
 			}
@@ -19099,7 +19101,7 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 	 */
 	if (dns_rdataset_isassociated(&cdnskey)) {
 		bool delete = false;
-		memset(algorithms, 0, sizeof(algorithms));
+		memset(algorithms, notexpected, sizeof(algorithms));
 		for (result = dns_rdataset_first(&cdnskey);
 		     result == ISC_R_SUCCESS;
 		     result = dns_rdataset_next(&cdnskey)) {
@@ -19113,7 +19115,7 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 			 * and 2 zero octets.
 			 */
 			if (crdata.length == 5U &&
-			    memcmp(crdata.data, "\0\0\003\0", 5) == 0)
+			    memcmp(crdata.data, "\0\0\3\0", 5) == 0)
 			{
 				delete = true;
 				continue;
@@ -19121,7 +19123,7 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 			CHECK(dns_rdata_tostruct(&crdata, &structcdnskey,
 						 NULL));
 			if (algorithms[structcdnskey.algorithm] == 0) {
-				algorithms[structcdnskey.algorithm] = 1;
+				algorithms[structcdnskey.algorithm] = expected;
 			}
 			for (result = dns_rdataset_first(&dnskey);
 			     result == ISC_R_SUCCESS;
@@ -19133,7 +19135,8 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 				    memcmp(crdata.data, rdata.data,
 					   rdata.length) == 0)
 				{
-					algorithms[structcdnskey.algorithm] = 2;
+					algorithms[structcdnskey.algorithm] =
+							 found;
 				}
 			}
 			if (result != ISC_R_NOMORE) {
@@ -19142,11 +19145,11 @@ dns_zone_cdscheck(dns_zone_t *zone, dns_db_t *db, dns_dbversion_t *version) {
 		}
 		for (i = 0; i < sizeof(algorithms); i++) {
 			if (delete) {
-				if (algorithms[i] != 0) {
+				if (algorithms[i] != notexpected) {
 					result = DNS_R_BADCDNSKEY;
 					goto failure;
 				}
-			} else if (algorithms[i] == 1) {
+			} else if (algorithms[i] == expected) {
 				result = DNS_R_BADCDNSKEY;
 				goto failure;
 			}