diff --git a/src/compiler/compile/render_dom/wrappers/Element/index.ts b/src/compiler/compile/render_dom/wrappers/Element/index.ts
index b724b17a9d..4687feaebf 100644
--- a/src/compiler/compile/render_dom/wrappers/Element/index.ts
+++ b/src/compiler/compile/render_dom/wrappers/Element/index.ts
@@ -602,7 +602,7 @@ export default class ElementWrapper extends Wrapper {
 		}
 
 		if (to_optimise_hydration) {
-			attributes.push(p`["data-svelte"]: true`);
+			attributes.push(p`["data-svelte-h"]: true`);
 		}
 
 		if (this.node.namespace === namespaces.svg) {
diff --git a/src/compiler/compile/render_ssr/handlers/Element.ts b/src/compiler/compile/render_ssr/handlers/Element.ts
index e6d2117f00..485f5e9ee3 100644
--- a/src/compiler/compile/render_ssr/handlers/Element.ts
+++ b/src/compiler/compile/render_ssr/handlers/Element.ts
@@ -161,10 +161,10 @@ export default function (node: Element, renderer: Renderer, options: RenderOptio
 
 	if (options.hydratable) {
 		if (node.children.length === 1 && node.children[0].type === 'RawMustacheTag') {
-			renderer.add_string(` data-svelte="${hash(JSON.stringify(node.children[0].expression.node))}"`);
+			renderer.add_string(` data-svelte-h="${hash(JSON.stringify(node.children[0].expression.node))}"`);
 			options = { ...options, optimised_html_hydration: true };
 		} else if (node.can_optimise_to_html_string && !options.has_added_svelte_hash) {
-			renderer.add_string(` data-svelte="${node.hash()}"`);
+			renderer.add_string(` data-svelte-h="${node.hash()}"`);
 			options = { ...options, has_added_svelte_hash: true };
 		}
 	}
diff --git a/src/runtime/internal/dom.ts b/src/runtime/internal/dom.ts
index a16bce8071..a892f3f18f 100644
--- a/src/runtime/internal/dom.ts
+++ b/src/runtime/internal/dom.ts
@@ -353,7 +353,7 @@ export function xlink_attr(node, attribute, value) {
 }
 
 export function get_svelte_dataset(node: HTMLElement) {
-	return node.dataset.svelte;
+	return node.dataset.svelteH;
 }
 
 export function get_binding_group_value(group, __value, checked) {
diff --git a/test/helpers.ts b/test/helpers.ts
index 8128f4ddf8..b08d069068 100644
--- a/test/helpers.ts
+++ b/test/helpers.ts
@@ -145,7 +145,7 @@ export function normalizeHtml(window, html, { removeDataSvelte = false, preserve
 		const node = window.document.createElement('div');
 		node.innerHTML = html
 			.replace(/(<!--.*?-->)/g, preserveComments ? '$1' : '')
-			.replace(/(data-svelte="[^"]+")/g, removeDataSvelte ? '' : '$1')
+			.replace(/(data-svelte-h="[^"]+")/g, removeDataSvelte ? '' : '$1')
 			.replace(/>[\s\r\n]+</g, '><')
 			.trim();
 		cleanChildren(node);
@@ -174,10 +174,10 @@ export function setupHtmlEqual(options: { removeDataSvelte?: boolean } = {}) {
 	assert.htmlEqualWithOptions = (actual: string, expected: string, { preserveComments, withoutNormalizeHtml }: { preserveComments?: boolean, withoutNormalizeHtml?: boolean }, message?: string) => {
 		assert.deepEqual(
 			withoutNormalizeHtml
-				? normalizeNewline(actual).replace(/(\sdata-svelte="[^"]+")/g, options.removeDataSvelte ? '' : '$1')
+				? normalizeNewline(actual).replace(/(\sdata-svelte-h="[^"]+")/g, options.removeDataSvelte ? '' : '$1')
 				: normalizeHtml(window, actual, { ...options, preserveComments }),
 			withoutNormalizeHtml
-				? normalizeNewline(expected).replace(/(\sdata-svelte="[^"]+")/g, options.removeDataSvelte ? '' : '$1')
+				? normalizeNewline(expected).replace(/(\sdata-svelte-h="[^"]+")/g, options.removeDataSvelte ? '' : '$1')
 				: normalizeHtml(window, expected, { ...options, preserveComments }),
 			message
 		);
diff --git a/test/hydration/samples/basic/_after.html b/test/hydration/samples/basic/_after.html
index 7c4ab6e7b9..6fd7fb9e47 100644
--- a/test/hydration/samples/basic/_after.html
+++ b/test/hydration/samples/basic/_after.html
@@ -1 +1 @@
-<h1 data-svelte="svelte-1vv3a6r">Hello world!</h1>
\ No newline at end of file
+<h1 data-svelte-h="svelte-1vv3a6r">Hello world!</h1>
\ No newline at end of file
diff --git a/test/hydration/samples/basic/_before.html b/test/hydration/samples/basic/_before.html
index 7c4ab6e7b9..6fd7fb9e47 100644
--- a/test/hydration/samples/basic/_before.html
+++ b/test/hydration/samples/basic/_before.html
@@ -1 +1 @@
-<h1 data-svelte="svelte-1vv3a6r">Hello world!</h1>
\ No newline at end of file
+<h1 data-svelte-h="svelte-1vv3a6r">Hello world!</h1>
\ No newline at end of file
diff --git a/test/hydration/samples/claim-static-incorrect-hash/_after.html b/test/hydration/samples/claim-static-incorrect-hash/_after.html
index 585c6b005d..3956ffe88a 100644
--- a/test/hydration/samples/claim-static-incorrect-hash/_after.html
+++ b/test/hydration/samples/claim-static-incorrect-hash/_after.html
@@ -1,8 +1,8 @@
-<div data-svelte="xxx">hello</div>
+<div data-svelte-h="xxx">hello</div>
 
-<div data-svelte="xxx"><div>bye</div></div>
+<div data-svelte-h="xxx"><div>bye</div></div>
 
-<div data-svelte="xxx">
+<div data-svelte-h="xxx">
 	<div>aaa</div>
 	<div>bbb</div>
 </div>
\ No newline at end of file
diff --git a/test/hydration/samples/claim-static-incorrect-hash/_before.html b/test/hydration/samples/claim-static-incorrect-hash/_before.html
index 59acf4d46d..9dd22f8c4f 100644
--- a/test/hydration/samples/claim-static-incorrect-hash/_before.html
+++ b/test/hydration/samples/claim-static-incorrect-hash/_before.html
@@ -1,8 +1,8 @@
-<div data-svelte="xxx">hello</div>
+<div data-svelte-h="xxx">hello</div>
 
-<div data-svelte="xxx"><div data-svelte="yyy">bye</div></div>
+<div data-svelte-h="xxx"><div data-svelte-h="yyy">bye</div></div>
 
-<div data-svelte="xxx">
-	<div data-svelte="yyy">aaa</div>
-	<div data-svelte="zzz">bbb</div>
+<div data-svelte-h="xxx">
+	<div data-svelte-h="yyy">aaa</div>
+	<div data-svelte-h="zzz">bbb</div>
 </div>
\ No newline at end of file
diff --git a/test/hydration/samples/component-in-element/_after.html b/test/hydration/samples/component-in-element/_after.html
index 127e868d6b..7e610c2946 100644
--- a/test/hydration/samples/component-in-element/_after.html
+++ b/test/hydration/samples/component-in-element/_after.html
@@ -1,3 +1,3 @@
 <div>
-	<p data-svelte="svelte-1x3hbnh">nested</p>
+	<p data-svelte-h="svelte-1x3hbnh">nested</p>
 </div>
\ No newline at end of file
diff --git a/test/hydration/samples/component-in-element/_before.html b/test/hydration/samples/component-in-element/_before.html
index 127e868d6b..7e610c2946 100644
--- a/test/hydration/samples/component-in-element/_before.html
+++ b/test/hydration/samples/component-in-element/_before.html
@@ -1,3 +1,3 @@
 <div>
-	<p data-svelte="svelte-1x3hbnh">nested</p>
+	<p data-svelte-h="svelte-1x3hbnh">nested</p>
 </div>
\ No newline at end of file
diff --git a/test/hydration/samples/component/_after.html b/test/hydration/samples/component/_after.html
index bd79430d0e..1dd7a4ec7e 100644
--- a/test/hydration/samples/component/_after.html
+++ b/test/hydration/samples/component/_after.html
@@ -1 +1 @@
-<p data-svelte="svelte-1x3hbnh">nested</p>
\ No newline at end of file
+<p data-svelte-h="svelte-1x3hbnh">nested</p>
\ No newline at end of file
diff --git a/test/hydration/samples/component/_before.html b/test/hydration/samples/component/_before.html
index bd79430d0e..1dd7a4ec7e 100644
--- a/test/hydration/samples/component/_before.html
+++ b/test/hydration/samples/component/_before.html
@@ -1 +1 @@
-<p data-svelte="svelte-1x3hbnh">nested</p>
\ No newline at end of file
+<p data-svelte-h="svelte-1x3hbnh">nested</p>
\ No newline at end of file
diff --git a/test/hydration/samples/element-nested/_after.html b/test/hydration/samples/element-nested/_after.html
index 0d1f487091..cfc87f4d37 100644
--- a/test/hydration/samples/element-nested/_after.html
+++ b/test/hydration/samples/element-nested/_after.html
@@ -1,3 +1,3 @@
-<div data-svelte="svelte-1aqf5aj">
+<div data-svelte-h="svelte-1aqf5aj">
 	<p>nested</p>
 </div>
\ No newline at end of file
diff --git a/test/hydration/samples/element-nested/_before.html b/test/hydration/samples/element-nested/_before.html
index 0d1f487091..cfc87f4d37 100644
--- a/test/hydration/samples/element-nested/_before.html
+++ b/test/hydration/samples/element-nested/_before.html
@@ -1,3 +1,3 @@
-<div data-svelte="svelte-1aqf5aj">
+<div data-svelte-h="svelte-1aqf5aj">
 	<p>nested</p>
 </div>
\ No newline at end of file
diff --git a/test/server-side-rendering/samples/head-meta-hydrate-duplicate/_expected.html b/test/server-side-rendering/samples/head-meta-hydrate-duplicate/_expected.html
index 0946c910dd..8edc2860a8 100644
--- a/test/server-side-rendering/samples/head-meta-hydrate-duplicate/_expected.html
+++ b/test/server-side-rendering/samples/head-meta-hydrate-duplicate/_expected.html
@@ -1 +1 @@
- <div data-svelte="svelte-156ixv6">Just a dummy page.</div>
\ No newline at end of file
+ <div data-svelte-h="svelte-156ixv6">Just a dummy page.</div>
\ No newline at end of file