diff --git a/demo/package.json b/demo/package.json
index f2e58dfb..2638293c 100644
--- a/demo/package.json
+++ b/demo/package.json
@@ -32,7 +32,6 @@
 		"@cartamd/plugin-math": "workspace:^",
 		"@cartamd/plugin-slash": "workspace:^",
 		"@cartamd/plugin-tikz": "workspace:^",
-		"@speed-highlight/core": "^1.1.11",
 		"carta-md": "workspace:^",
 		"katex": "^0.16.7"
 	}
diff --git a/packages/carta-md/package.json b/packages/carta-md/package.json
index 01fecf76..96959827 100644
--- a/packages/carta-md/package.json
+++ b/packages/carta-md/package.json
@@ -36,7 +36,7 @@
 	},
 	"type": "module",
 	"dependencies": {
-		"@speed-highlight/core": "^1.2.2",
+		"@speed-highlight/core": "1.2.2",
 		"marked": "^6.0.0",
 		"marked-gfm-heading-id": "^3.0.5",
 		"marked-mangle": "^1.1.1"
diff --git a/packages/carta-md/src/lib/internal/carta.ts b/packages/carta-md/src/lib/internal/carta.ts
index 0cf9aa19..d1f3218c 100644
--- a/packages/carta-md/src/lib/internal/carta.ts
+++ b/packages/carta-md/src/lib/internal/carta.ts
@@ -1,4 +1,4 @@
-import { marked, type MarkedExtension } from 'marked';
+import { Marked, type MarkedExtension } from 'marked';
 import type { CartaHistoryOptions } from './history';
 import { CartaInput } from './input';
 import {
@@ -169,6 +169,8 @@ export class Carta {
 	public readonly cartaListeners: CartaListeners;
 	public readonly components: CartaExtensionComponents;
 	public readonly dispatcher = new EventTarget();
+	public readonly markedAsync = new Marked();
+	public readonly markedSync = new Marked();
 
 	private _input: CartaInput | undefined;
 	private _renderer: CartaRenderer | undefined;
@@ -234,22 +236,25 @@ export class Carta {
 
 		// Load default marked extensions
 		if (options?.mangle !== false) {
-			marked.use(mangle());
+			this.useMarkedExtension(mangle());
 		} else {
-			marked.use({ mangle: false });
+			this.useMarkedExtension({ mangle: false });
 		}
 
 		if (options?.gfmHeadingId !== false) {
-			marked.use(gfmHeadingId(options?.gfmHeadingId));
+			this.useMarkedExtension(gfmHeadingId(options?.gfmHeadingId));
 		} else {
-			marked.use({ headerIds: false });
+			this.useMarkedExtension({ headerIds: false });
 		}
 
 		// Load marked extensions
 		const markedExtensions = this.options?.extensions
 			?.flatMap((ext) => ext.markedExtensions)
 			.filter((ext) => ext != null) as MarkedExtension[] | undefined;
-		if (markedExtensions) marked.use(...markedExtensions);
+		if (markedExtensions)
+			markedExtensions.forEach((ext) => {
+				this.useMarkedExtension(ext);
+			});
 
 		// Load highlight custom language
 		import('./shj.js')
@@ -272,13 +277,19 @@ export class Carta {
 		}
 	}
 
+	private useMarkedExtension(exts: MarkedExtension) {
+		this.markedAsync.use(exts);
+		if (!exts.async) this.markedSync.use(exts);
+	}
+
 	/**
 	 * Render markdown to html asynchronously.
 	 * @param markdown Markdown input.
 	 * @returns Rendered html.
 	 */
 	public async render(markdown: string): Promise<string> {
-		const dirty = await marked.parse(markdown, { async: true });
+		const dirty = await this.markedAsync.parse(markdown, { async: true });
+		if (!dirty) return '';
 		this.dispatcher.dispatchEvent(
 			new CustomEvent<{ carta: Carta }>('carta-render', { detail: { carta: this } })
 		);
@@ -291,7 +302,8 @@ export class Carta {
 	 * @returns Rendered html.
 	 */
 	public renderSSR(markdown: string): string {
-		const dirty = marked.parse(markdown, { async: false });
+		const dirty = this.markedSync.parse(markdown, { async: false });
+		if (typeof dirty != 'string') return '';
 		this.dispatcher.dispatchEvent(
 			new CustomEvent<{ carta: Carta }>('carta-render-ssr', { detail: { carta: this } })
 		);
diff --git a/packages/plugin-code/package.json b/packages/plugin-code/package.json
index 3fbdc982..ab5009fb 100644
--- a/packages/plugin-code/package.json
+++ b/packages/plugin-code/package.json
@@ -23,8 +23,7 @@
 		"marked": "^6.0.0"
 	},
 	"peerDependencies": {
-		"carta-md": "^2.1.0",
-		"marked": "^4.3.0"
+		"carta-md": "^2.1.0"
 	},
 	"files": [
 		"dist"
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 8ee90603..5217a2cc 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -60,9 +60,6 @@ importers:
       '@cartamd/plugin-tikz':
         specifier: workspace:^
         version: link:../packages/plugin-tikz
-      '@speed-highlight/core':
-        specifier: ^1.1.11
-        version: 1.1.11
       carta-md:
         specifier: workspace:^
         version: link:../packages/carta-md
@@ -101,7 +98,7 @@ importers:
   packages/carta-md:
     dependencies:
       '@speed-highlight/core':
-        specifier: ^1.2.2
+        specifier: 1.2.2
         version: 1.2.2
       marked:
         specifier: ^6.0.0
@@ -754,10 +751,6 @@ packages:
       string-argv: 0.3.1
     dev: true
 
-  /@speed-highlight/core@1.1.11:
-    resolution: {integrity: sha512-KtUCQahL7WjK8zKEhWwzBa/7t6wimmOF9BFS/gIbVE48BwNEK7NafOkwzfYRF7D6RjENsP2aJDZRANwHDncqnw==}
-    dev: false
-
   /@speed-highlight/core@1.2.2:
     resolution: {integrity: sha512-Yb3ewAUq7QwLbU+vF28dxkOmBJG5bHUVWZWQBnUt2GIhVWdiShKcE6kBMsCRXvD8AuK7gy0rR4qNckqZnCzEFw==}
     dev: false
@@ -776,7 +769,7 @@ packages:
     peerDependencies:
       '@sveltejs/kit': ^1.0.0
     dependencies:
-      '@sveltejs/kit': 1.15.9(svelte@3.55.1)(vite@4.3.9)
+      '@sveltejs/kit': 1.15.9(svelte@3.58.0)(vite@4.3.9)
       import-meta-resolve: 2.2.2
     dev: true