diff --git a/docs/custom.md b/docs/custom.md
index 65753e13..10e2e96c 100644
--- a/docs/custom.md
+++ b/docs/custom.md
@@ -30,8 +30,8 @@ Feel free to open issues to extend its configuration options.
 
 - `"domain"` is the domain to update. It can be `example.com` (root domain), `sub.example.com` (subdomain of `example.com`) or `*.example.com` for the wildcard.
 - `"url"` is the URL to update your records and should contain all the information EXCEPT the IP address to update
-- `"ipv4key"` is the URL query parameter name for the IPv4 address, for example `ipv4` will be added to the URL with `&ipv4=1.2.3.4`.
-- `"ipv6key"` is the URL query parameter name for the IPv6 address, for example `ipv6` will be added to the URL with `&ipv6=::aaff`. Even if you don't use IPv6, this must be set to something.
+- `"ipv4key"` is the URL query parameter name for the IPv4 address, for example `ipv4` will be added to the URL with `&ipv4=1.2.3.4`. In the rare case you do not wish to send an IPv4 query parameter to the registrar API when updating your A (IPv4) record, leave it to `"ipv4key": ""`.
+- `"ipv6key"` is the URL query parameter name for the IPv6 address, for example `ipv6` will be added to the URL with `&ipv6=::aaff`. In the rare case you do not wish to send an IPv6 query parameter to the registrar API when updating your AAAA (IPv6) record, leave it to `"ipv6key": ""`.
 - `"success_regex"` is a regular expression to match the response from the server to determine if the update was successful. You can use [regex101.com](https://regex101.com/) to find the regular expression you want. For example `good` would match any response containing the word "good".
 
 ### Optional parameters
diff --git a/internal/provider/errors/validation.go b/internal/provider/errors/validation.go
index 6d930a77..9a11ca99 100644
--- a/internal/provider/errors/validation.go
+++ b/internal/provider/errors/validation.go
@@ -19,8 +19,6 @@ var (
 	ErrGCPProjectNotSet       = errors.New("GCP project is not set")
 	ErrDomainNotValid         = errors.New("domain is not valid")
 	ErrOwnerWildcard          = errors.New(`owner cannot be "*"`)
-	ErrIPv4KeyNotSet          = errors.New("IPv4 key is not set")
-	ErrIPv6KeyNotSet          = errors.New("IPv6 key is not set")
 	ErrKeyNotSet              = errors.New("key is not set")
 	ErrKeyNotValid            = errors.New("key is not valid")
 	ErrPasswordNotSet         = errors.New("password is not set")
diff --git a/internal/provider/providers/custom/provider.go b/internal/provider/providers/custom/provider.go
index 92cc72c1..514ce7df 100644
--- a/internal/provider/providers/custom/provider.go
+++ b/internal/provider/providers/custom/provider.go
@@ -49,7 +49,7 @@ func New(data json.RawMessage, domain, owner string,
 		return nil, fmt.Errorf("parsing URL: %w", err)
 	}
 
-	err = validateSettings(domain, parsedURL, extraSettings.IPv4Key, extraSettings.IPv6Key, extraSettings.SuccessRegex)
+	err = validateSettings(domain, parsedURL, extraSettings.SuccessRegex)
 	if err != nil {
 		return nil, fmt.Errorf("validating provider specific settings: %w", err)
 	}
@@ -67,7 +67,7 @@ func New(data json.RawMessage, domain, owner string,
 }
 
 func validateSettings(domain string, url *url.URL,
-	ipv4Key, ipv6Key string, successRegex regexp.Regexp,
+	successRegex regexp.Regexp,
 ) (err error) {
 	err = utils.CheckDomain(domain)
 	if err != nil {
@@ -79,10 +79,6 @@ func validateSettings(domain string, url *url.URL,
 		return fmt.Errorf("%w", errors.ErrURLNotSet)
 	case url.Scheme != "https":
 		return fmt.Errorf("%w: %s", errors.ErrURLNotHTTPS, url.Scheme)
-	case ipv4Key == "":
-		return fmt.Errorf("%w", errors.ErrIPv4KeyNotSet)
-	case ipv6Key == "":
-		return fmt.Errorf("%w", errors.ErrIPv6KeyNotSet)
 	case successRegex.String() == "":
 		return fmt.Errorf("%w", errors.ErrSuccessRegexNotSet)
 	default:
@@ -138,7 +134,9 @@ func (p *Provider) Update(ctx context.Context, client *http.Client, ip netip.Add
 	if ip.Is6() {
 		ipKey = p.ipv6Key
 	}
-	values.Set(ipKey, ip.String())
+	if ipKey != "" {
+		values.Set(ipKey, ip.String())
+	}
 	p.url.RawQuery = values.Encode()
 
 	request, err := http.NewRequestWithContext(ctx, http.MethodGet, p.url.String(), nil)