diff --git a/packages/core/src/utils/getSchema.ts b/packages/core/src/utils/getSchema.ts
index 72d3db62..ee0bed4d 100644
--- a/packages/core/src/utils/getSchema.ts
+++ b/packages/core/src/utils/getSchema.ts
@@ -6,6 +6,7 @@ import getRenderedAttributes from './getRenderedAttributes'
 import isEmptyObject from './isEmptyObject'
 import injectExtensionAttributesToParseRule from './injectExtensionAttributesToParseRule'
 import callOrReturn from './callOrReturn'
+import mergeAttributes from './mergeAttributes'
 
 function cleanUpSchemaItem<T>(data: T) {
   return Object.fromEntries(Object.entries(data).filter(([key, value]) => {
@@ -50,7 +51,10 @@ export default function getSchema(extensions: Extensions): Schema {
     if (extension.renderHTML) {
       schema.toDOM = node => (extension.renderHTML as Function)?.bind(context)({
         node,
-        HTMLAttributes: getRenderedAttributes(node, extensionAttributes),
+        HTMLAttributes: mergeAttributes(
+          extension.options.HTMLAttributes,
+          getRenderedAttributes(node, extensionAttributes),
+        ),
       })
     }
 
@@ -79,7 +83,10 @@ export default function getSchema(extensions: Extensions): Schema {
     if (extension.renderHTML) {
       schema.toDOM = mark => (extension.renderHTML as Function)?.bind(context)({
         mark,
-        HTMLAttributes: getRenderedAttributes(mark, extensionAttributes),
+        HTMLAttributes: mergeAttributes(
+          extension.options.HTMLAttributes,
+          getRenderedAttributes(mark, extensionAttributes),
+        ),
       })
     }
 
diff --git a/packages/core/src/utils/mergeAttributes.ts b/packages/core/src/utils/mergeAttributes.ts
index 733c8cb9..558bdf21 100644
--- a/packages/core/src/utils/mergeAttributes.ts
+++ b/packages/core/src/utils/mergeAttributes.ts
@@ -1,26 +1,28 @@
 import { AnyObject } from '../types'
 
-export default function mergeAttributes(...object: AnyObject[]) {
-  return object.reduce((items, item) => {
-    const mergedAttributes = { ...items }
+export default function mergeAttributes(...objects: AnyObject[]) {
+  return objects
+    .filter(item => !!item)
+    .reduce((items, item) => {
+      const mergedAttributes = { ...items }
 
-    Object.entries(item).forEach(([key, value]) => {
-      const exists = mergedAttributes[key]
+      Object.entries(item).forEach(([key, value]) => {
+        const exists = mergedAttributes[key]
 
-      if (!exists) {
-        mergedAttributes[key] = value
-        return
-      }
+        if (!exists) {
+          mergedAttributes[key] = value
+          return
+        }
 
-      if (key === 'class') {
-        mergedAttributes[key] = [mergedAttributes[key], value].join(' ')
-      } else if (key === 'style') {
-        mergedAttributes[key] = [mergedAttributes[key], value].join('; ')
-      } else {
-        mergedAttributes[key] = value
-      }
-    })
+        if (key === 'class') {
+          mergedAttributes[key] = [mergedAttributes[key], value].join(' ')
+        } else if (key === 'style') {
+          mergedAttributes[key] = [mergedAttributes[key], value].join('; ')
+        } else {
+          mergedAttributes[key] = value
+        }
+      })
 
-    return mergedAttributes
-  }, {})
+      return mergedAttributes
+    }, {})
 }
diff --git a/packages/extension-link/src/index.ts b/packages/extension-link/src/index.ts
index 2bf0dd2e..cd8c1a28 100644
--- a/packages/extension-link/src/index.ts
+++ b/packages/extension-link/src/index.ts
@@ -1,9 +1,4 @@
-import {
-  Command,
-  createMark,
-  markPasteRule,
-  mergeAttributes,
-} from '@tiptap/core'
+import { Command, createMark, markPasteRule } from '@tiptap/core'
 import { Plugin, PluginKey } from 'prosemirror-state'
 
 export interface LinkOptions {
@@ -46,7 +41,7 @@ const Link = createMark({
   },
 
   renderHTML({ HTMLAttributes }) {
-    return ['a', mergeAttributes(HTMLAttributes, { rel: this.options.HTMLAttributes.rel }), 0]
+    return ['a', HTMLAttributes, 0]
   },
 
   addCommands() {
diff --git a/tests/cypress/integration/core/mergeAttributes.spec.ts b/tests/cypress/integration/core/mergeAttributes.spec.ts
index 5a6a24e0..fcb2aac5 100644
--- a/tests/cypress/integration/core/mergeAttributes.spec.ts
+++ b/tests/cypress/integration/core/mergeAttributes.spec.ts
@@ -57,4 +57,13 @@ describe('mergeAttributes', () => {
       style: 'color: red; background: green',
     })
   })
+
+  it('should ignore falsy values', () => {
+    // @ts-expect-error
+    const value = mergeAttributes(undefined, { class: 'foo' })
+
+    expect(value).to.deep.eq({
+      class: 'foo',
+    })
+  })
 })