diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index bb0cbf7a1a485c1cabd1cfe6cfb6628217187ff8..75e0e73e8b794f4b8b41f4f51e2ed05184e478d1 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -11,6 +11,7 @@ For a detailed view of what's changed, refer to the {url-repo}/commits[commit hi
 * add `build.stderr` key to Assembler config to control stderr lines emitted by command (`ignore`, `print`, `log`) (#112)
 * route stderr lines from command to Antora log if value of `build.stderr` key is `log` (#112)
 * introduce `embedReferenceStyle` property on exporter's converter object to control how image targets are rewritten (when embedded or bundled) (#100)
+* assign intrinsic attributes assembler-filetype and assembler-filetype-<filetype> (#122)
 
 === Changed
 
diff --git a/packages/assembler/lib/assemble-content.js b/packages/assembler/lib/assemble-content.js
index 2dca8ec85f51b2bd4f29ed0dcbd0c9a147c66f37..d1c48c738ea7eeb7c28a0a9b03fec2c0f4529717 100644
--- a/packages/assembler/lib/assemble-content.js
+++ b/packages/assembler/lib/assemble-content.js
@@ -51,6 +51,11 @@ async function assembleContent (playbook, contentCatalog, converter, { configSou
   } else {
     buildConfig.dir ??= ospath.join(playbook.dir ?? process.cwd(), 'build/assembler')
   }
+  if (targetExtname) {
+    const targetFiletype = targetExtname.slice(1)
+    intrinsicAttributes[`assembler-filetype-${targetFiletype}`] = ''
+    intrinsicAttributes['assembler-filetype'] = targetFiletype
+  }
   Object.assign(assemblerConfig.asciidoc.attributes, intrinsicAttributes)
   const assemblyFiles = produceAssemblyFiles(
     loadAsciiDoc,
diff --git a/packages/assembler/test/assemble-content-test.js b/packages/assembler/test/assemble-content-test.js
index 011d9c035e90cf8af3e38bc2d9d8978945cd67fe..42414b33c04e513311291e783acb7e36cf7efeaf 100644
--- a/packages/assembler/test/assemble-content-test.js
+++ b/packages/assembler/test/assemble-content-test.js
@@ -67,6 +67,8 @@ describe('assembleContent()', () => {
     const expectedConvertAttributes = {
       'assembler-backend': 'pdf',
       'assembler-backend-pdf': '',
+      'assembler-filetype': 'pdf',
+      'assembler-filetype-pdf': '',
       'assembler-profile': 'pdf',
       'assembler-profile-pdf': '',
       docdir: ospath.dirname(ospath.join(expectedOutdir, 'index.adoc')),