diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
index f94d4f0ee8..538e410855 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
@@ -105,6 +105,16 @@ export function RegularElement(node, context) {
 				break;
 
 			case 'Attribute':
+				// `is` attributes need to be part of the template, otherwise they break
+				if (attribute.name === 'is' && context.state.metadata.namespace === 'html') {
+					const { value } = build_attribute_value(attribute.value, context);
+
+					if (value.type === 'Literal' && typeof value.value === 'string') {
+						context.state.template.push(` is="${escape_html(value.value, true)}"`);
+						continue;
+					}
+				}
+
 				attributes.push(attribute);
 				lookup.set(attribute.name, attribute);
 				break;
@@ -243,7 +253,7 @@ export function RegularElement(node, context) {
 				attribute.name !== 'autofocus' &&
 				(attribute.value === true || is_text_attribute(attribute))
 			) {
-				const name = get_attribute_name(node, attribute, context);
+				const name = get_attribute_name(node, attribute);
 				const value = is_text_attribute(attribute) ? attribute.value[0].data : true;
 
 				if (name !== 'class' || value) {
@@ -479,15 +489,6 @@ function build_element_spread_attributes(attributes, context, element, element_i
 		if (attribute.type === 'Attribute') {
 			const { value } = build_attribute_value(attribute.value, context);
 
-			if (
-				attribute.name === 'is' &&
-				value.type === 'Literal' &&
-				context.state.metadata.namespace === 'html'
-			) {
-				context.state.template.push(` is="${escape_html(value.value, true)}"`);
-				continue;
-			}
-
 			if (
 				is_event_attribute(attribute) &&
 				(get_attribute_expression(attribute).type === 'ArrowFunctionExpression' ||
@@ -568,7 +569,7 @@ function build_element_spread_attributes(attributes, context, element, element_i
  */
 function build_element_attribute_update_assignment(element, node_id, attribute, context) {
 	const state = context.state;
-	const name = get_attribute_name(element, attribute, context);
+	const name = get_attribute_name(element, attribute);
 	const is_svg = context.state.metadata.namespace === 'svg' || element.name === 'svg';
 	const is_mathml = context.state.metadata.namespace === 'mathml';
 	let { has_call, value } = build_attribute_value(attribute.value, context);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/element.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/element.js
index b46392bf11..dc14fc80ab 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/element.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/element.js
@@ -101,6 +101,7 @@ export function build_class_directives(
 /**
  * @param {AST.Attribute['value']} value
  * @param {ComponentContext} context
+ * @returns {{ value: Expression, has_state: boolean, has_call: boolean }}
  */
 export function build_attribute_value(value, context) {
 	if (value === true) {
@@ -127,9 +128,8 @@ export function build_attribute_value(value, context) {
 /**
  * @param {AST.RegularElement | AST.SvelteElement} element
  * @param {AST.Attribute} attribute
- * @param {{ state: { metadata: { namespace: Namespace }}}} context
  */
-export function get_attribute_name(element, attribute, context) {
+export function get_attribute_name(element, attribute) {
 	if (!element.metadata.svg && !element.metadata.mathml) {
 		return normalize_attribute(attribute.name);
 	}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
index 7d2c5d78a1..21b902d5c2 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
@@ -36,6 +36,7 @@ export function get_states_and_calls(values) {
  * @param {Array<AST.Text | AST.ExpressionTag>} values
  * @param {(node: SvelteNode, state: any) => any} visit
  * @param {ComponentClientTransformState} state
+ * @returns {{ value: Expression, has_state: boolean, has_call: boolean }}
  */
 export function build_template_literal(values, visit, state) {
 	/** @type {Expression[]} */
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/element.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/element.js
index a968d646ad..c386c4f7c0 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/element.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/element.js
@@ -217,7 +217,7 @@ export function build_element_attributes(node, context) {
 	} else {
 		for (const attribute of /** @type {AST.Attribute[]} */ (attributes)) {
 			if (attribute.value === true || is_text_attribute(attribute)) {
-				const name = get_attribute_name(node, attribute, context);
+				const name = get_attribute_name(node, attribute);
 				const literal_value = /** @type {Literal} */ (
 					build_attribute_value(
 						attribute.value,
@@ -239,7 +239,7 @@ export function build_element_attributes(node, context) {
 				continue;
 			}
 
-			const name = get_attribute_name(node, attribute, context);
+			const name = get_attribute_name(node, attribute);
 			const value = build_attribute_value(
 				attribute.value,
 				context,
@@ -264,9 +264,8 @@ export function build_element_attributes(node, context) {
 /**
  * @param {AST.RegularElement | AST.SvelteElement} element
  * @param {AST.Attribute} attribute
- * @param {{ state: { namespace: Namespace }}} context
  */
-function get_attribute_name(element, attribute, context) {
+function get_attribute_name(element, attribute) {
 	let name = attribute.name;
 	if (!element.metadata.svg && !element.metadata.mathml) {
 		name = name.toLowerCase();
@@ -334,7 +333,7 @@ function build_element_spread_attributes(
 	const object = b.object(
 		attributes.map((attribute) => {
 			if (attribute.type === 'Attribute') {
-				const name = get_attribute_name(element, attribute, context);
+				const name = get_attribute_name(element, attribute);
 				const value = build_attribute_value(
 					attribute.value,
 					context,