diff --git a/.changeset/four-clocks-buy.md b/.changeset/four-clocks-buy.md
new file mode 100644
index 0000000..c2f4aac
--- /dev/null
+++ b/.changeset/four-clocks-buy.md
@@ -0,0 +1,5 @@
+---
+"remark-fff": patch
+---
+
+Version 1.2.0-alpha.2
diff --git a/packages/remark-fff/package.json b/packages/remark-fff/package.json
index 07fc5d2..16c464a 100644
--- a/packages/remark-fff/package.json
+++ b/packages/remark-fff/package.json
@@ -47,6 +47,7 @@
     "api-extractor": "api-extractor run --local --verbose"
   },
   "dependencies": {
+    "@fastify/deepmerge": "^1.3.0",
     "fff-flavored-frontmatter": "workspace:*",
     "unified": "^11.0.4"
   },
diff --git a/packages/remark-fff/src/plugin.ts b/packages/remark-fff/src/plugin.ts
index 80b12f0..c8abf04 100644
--- a/packages/remark-fff/src/plugin.ts
+++ b/packages/remark-fff/src/plugin.ts
@@ -1,5 +1,6 @@
 import type { Plugin, Transformer } from 'unified'
 
+import deepmerge from '@fastify/deepmerge'
 import { strict, transform } from 'fff-flavored-frontmatter'
 
 import type { RemarkFFFOptions } from './types'
@@ -19,6 +20,7 @@ export const remarkFFF: Plugin<[RemarkFFFOptions]>
     },
   ): Transformer =>
     (_tree, file) => {
+      const merge = deepmerge({ all: true })
       let targets: string[] | undefined
 
       // Compatible with old target parameters before 1.2.
@@ -62,9 +64,9 @@ export const remarkFFF: Plugin<[RemarkFFFOptions]>
       )
 
       file.data = targets
-        ? {
-            ...file.data,
-            ...targets.reduceRight((output, key) => ({ [key]: output }), output),
-          }
+        ? merge(
+          file.data,
+          targets.reduceRight((output, key) => ({ [key]: output }), output),
+        )
         : output
     }
diff --git a/packages/remark-fff/test/frontmatter.spec.ts b/packages/remark-fff/test/frontmatter.spec.ts
index 95b8e7c..fde88ea 100644
--- a/packages/remark-fff/test/frontmatter.spec.ts
+++ b/packages/remark-fff/test/frontmatter.spec.ts
@@ -13,16 +13,22 @@ describe('remark-fff', () => {
   it('mdsvex-hugo', () => {
     const file = new VFile({
       data: {
+        a: 'b',
         fm: {
           draft: true,
           images: 'https://fff.js.org/glowing_star.svg',
         },
       },
     })
-    const { fm } = remark().use(remarkFrontmatter).use(remarkFFF, {
-      presets: [hugo],
-      target: 'mdsvex',
-    }).processSync(file).data as { fm: FFFFlavoredFrontmatter }
+    const { a, fm } = remark()
+      .use(remarkFrontmatter).use(remarkFFF, {
+        presets: [hugo],
+        target: 'mdsvex',
+      }).processSync(file).data as {
+        a: string
+        fm: FFFFlavoredFrontmatter
+      }
+    expect(a).toEqual('b')
     // expect(fm.image).toEqual('https://fff.js.org/glowing_star.svg')
     expect(fm.flags).toEqual(['draft'])
   })
@@ -30,6 +36,7 @@ describe('remark-fff', () => {
     const file = new VFile({
       data: {
         astro: {
+          a: 'b',
           frontmatter: {
             categories: ['foo', 'bar', 'baz'],
             date: '2023-01-01',
@@ -39,15 +46,17 @@ describe('remark-fff', () => {
         },
       },
     })
-    const { frontmatter: fm } = remark()
+    const { a, frontmatter: fm } = remark()
       .use(remarkFrontmatter)
       .use(remarkFFF, {
         presets: [hexo],
         target: 'astro',
       })
       .processSync(file).data.astro as {
+        a: string
         frontmatter: FFFFlavoredFrontmatter
       }
+    expect(a).toEqual('b')
     expect(fm.created).toEqual('2023-01-01')
     expect(fm.summary).toEqual('lorem ipsum')
     // expect(fm.tags).toEqual(['fooo', 'baar', 'baaz', 'foo', 'bar', 'baz'])
@@ -142,6 +151,9 @@ describe('remark-fff strict mode', () => {
               },
             },
           },
+          e: {
+            f: 'g',
+          },
         },
       },
     })
@@ -151,7 +163,13 @@ describe('remark-fff strict mode', () => {
         presets: [{ created: 'date' }],
         target: ['a', 'b', 'c', 'd'],
       })
-      .processSync(file).data as { a: { b: { c: { d: FFFFlavoredFrontmatter } } } }
+      .processSync(file).data as {
+        a: {
+          b: { c: { d: FFFFlavoredFrontmatter } }
+          e: { f: string }
+        }
+      }
     expect(data.a.b.c.d.created).toEqual('2023-12-25')
+    expect(data.a.e.f).toEqual('g')
   })
 })
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 809225b..ff0115a 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -147,6 +147,9 @@ importers:
 
   packages/remark-fff:
     dependencies:
+      '@fastify/deepmerge':
+        specifier: ^1.3.0
+        version: 1.3.0
       fff-flavored-frontmatter:
         specifier: workspace:*
         version: link:../fff-flavored-frontmatter
@@ -2204,6 +2207,10 @@ packages:
     engines: {node: ^12.22.0 || ^14.17.0 || >=16.0.0}
     dev: true
 
+  /@fastify/deepmerge@1.3.0:
+    resolution: {integrity: sha512-J8TOSBq3SoZbDhM9+R/u77hP93gz/rajSA+K2kGyijPpORPWUXHUpTaleoj+92As0S9uPRP7Oi8IqMf0u+ro6A==}
+    dev: false
+
   /@humanwhocodes/config-array@0.11.13:
     resolution: {integrity: sha512-JSBDMiDKSzQVngfRjOdFXgFfklaXI4K9nLF49Auh21lmBWRLIK3+xTErTWD4KU54pb6coM6ESE7Awz/FNU3zgQ==}
     engines: {node: '>=10.10.0'}