diff --git a/src/dns.js b/src/dns.js
index 1d06eae98..39bee25d7 100644
--- a/src/dns.js
+++ b/src/dns.js
@@ -222,6 +222,11 @@ function makeWildcard(fqdn) {
 }
 
 async function registerLocation(location, options, recordType, recordValue) {
+    assert.strictEqual(typeof location, 'object');
+    assert.strictEqual(typeof options, 'object');
+    assert.strictEqual(typeof recordType, 'string');
+    assert.strictEqual(typeof recordValue, 'string');
+
     const overwriteDns = options.overwriteDns || false;
 
     // get the current record before updating it
@@ -267,13 +272,28 @@ async function registerLocations(locations, options, progressCallback) {
                 await removeDnsRecords(location.subdomain, location.domain, 'CNAME', values);
             }
 
-            if (ipv4) await registerLocation(location, options, 'A', ipv4);
-            if (ipv6) await registerLocation(location, options, 'AAAA', ipv6);
+            if (ipv4) {
+                await registerLocation(location, options, 'A', ipv4);
+            } else {
+                const [error, values] = await safe(getDnsRecords(location.subdomain, location.domain, 'A'));
+                if (!error && values.length) await safe(removeDnsRecords(location.subdomain, location.domain, 'A', values), { debug });
+            }
+
+            if (ipv6) {
+                await registerLocation(location, options, 'AAAA', ipv6);
+            } else {
+                const [error, values] = await safe(getDnsRecords(location.subdomain, location.domain, 'AAAA'));
+                if (!error && values.length) await safe(removeDnsRecords(location.subdomain, location.domain, 'AAAA', values), { debug });
+            }
         });
     }
 }
 
 async function unregisterLocation(location, recordType, recordValue) {
+    assert.strictEqual(typeof location, 'object');
+    assert.strictEqual(typeof recordType, 'string');
+    assert.strictEqual(typeof recordValue, 'string');
+
     const [error] = await safe(removeDnsRecords(location.subdomain, location.domain, recordType, [ recordValue ]));
     if (!error || error.reason === BoxError.NOT_FOUND) return;
 
@@ -313,9 +333,8 @@ async function syncDnsRecords(options, progressCallback) {
     const { domain:mailDomain, fqdn:mailFqdn, subdomain:mailSubdomain } = await mailServer.getLocation();
     const dashboardLocation = await dashboard.getLocation();
 
-    const allApps = await apps.list();
-
-    let progress = 1, errors = [];
+    const allApps = await apps.list(), errors = [];
+    let progress = 1;
 
     // we sync by domain only to get some nice progress
     for (const domain of allDomains) {
diff --git a/src/dns/cloudflare.js b/src/dns/cloudflare.js
index 005800b03..fd457f1b3 100644
--- a/src/dns/cloudflare.js
+++ b/src/dns/cloudflare.js
@@ -45,7 +45,7 @@ function translateRequestError(result) {
         if (typeof result.body.error === 'string') {
             message = `message: ${result.body.error} statusCode: ${result.statusCode}`;
         } else if (Array.isArray(result.body.errors) && result.body.errors.length > 0) {
-            let error = result.body.errors[0];
+            const error = result.body.errors[0];
             message = `message: ${error.message} statusCode: ${result.statusCode} code:${error.code}`;
         }
         return new BoxError(BoxError.ACCESS_DENIED, message);