diff --git a/src/from-markdown.ts b/src/from-markdown.ts
index 9a7d945..b9396c6 100644
--- a/src/from-markdown.ts
+++ b/src/from-markdown.ts
@@ -4,7 +4,7 @@
  * Version: 2.1.0
  * License: MIT (https://github.com/syntax-tree/mdast-util-directive/blob/main/license)
  */
-import type { Token } from 'micromark-util-types'
+import type { Token } from './micromark-extension/types'
 import { parseEntities } from 'parse-entities'
 import { kebabCase } from 'scule'
 
diff --git a/src/micromark-extension/factory-attributes.ts b/src/micromark-extension/factory-attributes.ts
index e3c9c9e..b0dff47 100644
--- a/src/micromark-extension/factory-attributes.ts
+++ b/src/micromark-extension/factory-attributes.ts
@@ -1,4 +1,4 @@
-import type { Effects, State } from 'micromark-util-types'
+import type { Effects, State, TokenTypeMap } from './types'
 import { factorySpace } from 'micromark-factory-space'
 import { factoryWhitespace } from 'micromark-factory-whitespace'
 
@@ -15,20 +15,20 @@ export default function createAttributes (
   effects: Effects,
   ok: State,
   nok: State,
-  attributesType: string,
-  attributesMarkerType: string,
-  attributeType: string,
-  attributeIdType: string,
-  attributeClassType: string,
-  attributeNameType: string,
-  attributeInitializerType: string,
-  attributeValueLiteralType: string,
-  attributeValueType: string,
-  attributeValueMarker: string,
-  attributeValueData: string,
+  attributesType: keyof TokenTypeMap,
+  attributesMarkerType: keyof TokenTypeMap,
+  attributeType: keyof TokenTypeMap,
+  attributeIdType: keyof TokenTypeMap,
+  attributeClassType: keyof TokenTypeMap,
+  attributeNameType: keyof TokenTypeMap,
+  attributeInitializerType: keyof TokenTypeMap,
+  attributeValueLiteralType: keyof TokenTypeMap,
+  attributeValueType: keyof TokenTypeMap,
+  attributeValueMarker: keyof TokenTypeMap,
+  attributeValueData: keyof TokenTypeMap,
   disallowEol?: boolean
 ) {
-  let type: string
+  let type: keyof TokenTypeMap
   let marker: number | undefined
 
   return start
@@ -74,9 +74,9 @@ export default function createAttributes (
   function shortcutStart (code: number) {
     effects.enter(attributeType)
     effects.enter(type)
-    effects.enter(type + 'Marker')
+    effects.enter(type + 'Marker' as keyof TokenTypeMap)
     effects.consume(code)
-    effects.exit(type + 'Marker')
+    effects.exit(type + 'Marker' as keyof TokenTypeMap)
     return shortcutStartAfter
   }
 
@@ -97,7 +97,7 @@ export default function createAttributes (
       return nok(code)
     }
 
-    effects.enter(type + 'Value')
+    effects.enter(type + 'Value' as keyof TokenTypeMap)
     effects.consume(code)
     return shortcut
   }
@@ -116,7 +116,7 @@ export default function createAttributes (
     }
 
     if (code === Codes.hash || code === Codes.dot || code === Codes.closingCurlyBracket || markdownLineEndingOrSpace(code)) {
-      effects.exit(type + 'Value')
+      effects.exit(type + 'Value' as keyof TokenTypeMap)
       effects.exit(type)
       effects.exit(attributeType)
       return between(code)
diff --git a/src/micromark-extension/factory-label.ts b/src/micromark-extension/factory-label.ts
index bb4186e..98e6227 100644
--- a/src/micromark-extension/factory-label.ts
+++ b/src/micromark-extension/factory-label.ts
@@ -1,4 +1,4 @@
-import type { Effects, State } from 'micromark-util-types'
+import type { Effects, State, TokenTypeMap } from './types'
 import { markdownLineEnding } from 'micromark-util-character'
 import { Codes } from './constants'
 
@@ -11,9 +11,9 @@ export default function createLabel (
   effects: Effects,
   ok: State,
   nok: State,
-  type: string,
-  markerType: string,
-  stringType: string,
+  type: keyof TokenTypeMap,
+  markerType: keyof TokenTypeMap,
+  stringType: keyof TokenTypeMap,
   disallowEol?: boolean
 ) {
   let size = 0
diff --git a/src/micromark-extension/factory-name.ts b/src/micromark-extension/factory-name.ts
index 9263cfd..1a96704 100644
--- a/src/micromark-extension/factory-name.ts
+++ b/src/micromark-extension/factory-name.ts
@@ -1,14 +1,14 @@
-import type { Effects, State, Code, TokenizeContext } from 'micromark-util-types'
+import type { Effects, State, Code, TokenizeContext, TokenTypeMap } from './types'
 import { asciiAlpha, asciiAlphanumeric } from 'micromark-util-character'
 import { Codes } from './constants'
 
-export default function createName (this: TokenizeContext, effects: Effects, ok: State, nok: State, nameType: string) {
+export default function createName (this: TokenizeContext, effects: Effects, ok: State, nok: State, nameType: keyof TokenTypeMap) {
   // eslint-disable-next-line @typescript-eslint/no-this-alias
   const self = this
 
   return start
 
-  function start (code: Code): State | void {
+  function start (code: Code): State | undefined {
     if (asciiAlpha(code)) {
       effects.enter(nameType)
       effects.consume(code)
@@ -18,7 +18,7 @@ export default function createName (this: TokenizeContext, effects: Effects, ok:
     return nok(code)
   }
 
-  function name (code: Code): State | void {
+  function name (code: Code): State {
     if (code === Codes.dash || code === Codes.underscore || asciiAlphanumeric(code)) {
       effects.consume(code)
       return name
@@ -26,6 +26,6 @@ export default function createName (this: TokenizeContext, effects: Effects, ok:
 
     effects.exit(nameType)
     // To do next major: disallow `-` at end of name too, for consistency.
-    return self.previous === Codes.underscore ? nok(code) : ok(code)
+    return self.previous === Codes.underscore ? nok(code)! : ok(code)!
   }
 }
diff --git a/src/micromark-extension/tokenize-attribute.ts b/src/micromark-extension/tokenize-attribute.ts
index 3e07e46..bd8aff3 100644
--- a/src/micromark-extension/tokenize-attribute.ts
+++ b/src/micromark-extension/tokenize-attribute.ts
@@ -1,4 +1,4 @@
-import type { Effects, State, Code, TokenizeContext } from 'micromark-util-types'
+import type { Effects, State, Code, TokenizeContext } from './types'
 import { markdownLineEnding } from 'micromark-util-character'
 import { Codes } from './constants'
 import createAttributes from './factory-attributes'
diff --git a/src/micromark-extension/tokenize-binding.ts b/src/micromark-extension/tokenize-binding.ts
index 4aab7cd..a126504 100644
--- a/src/micromark-extension/tokenize-binding.ts
+++ b/src/micromark-extension/tokenize-binding.ts
@@ -1,4 +1,4 @@
-import type { Effects, State, Code, TokenizeContext } from 'micromark-util-types'
+import type { Effects, State, Code, TokenizeContext } from './types'
 import { Codes } from './constants'
 
 function attempClose (this: TokenizeContext, effects: Effects, ok: State, nok: State) {
@@ -38,7 +38,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return secondBracket
   }
 
-  function secondBracket (code: Code): void | State {
+  function secondBracket (code: Code): undefined | State {
     if (code !== Codes.openingCurlyBracket) {
       return nok(code)
     }
@@ -49,7 +49,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return content
   }
 
-  function content (code: Code): void | State {
+  function content (code: Code): undefined | State {
     if (code === Codes.closingCurlyBracket) {
       return effects.attempt({ tokenize: attempClose, partial: true }, close, (code) => {
         effects.consume(code)
@@ -61,7 +61,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return content
   }
 
-  function close (code: Code): void | State {
+  function close (code: Code): undefined | State {
     return ok(code)
   }
 }
diff --git a/src/micromark-extension/tokenize-container-indented.ts b/src/micromark-extension/tokenize-container-indented.ts
index 6c94fca..d461ad4 100644
--- a/src/micromark-extension/tokenize-container-indented.ts
+++ b/src/micromark-extension/tokenize-container-indented.ts
@@ -1,4 +1,4 @@
-import type { Effects, State, TokenizeContext, Code } from 'micromark-util-types'
+import type { Effects, State, TokenizeContext, Code } from './types'
 import { codeFenced } from 'micromark-core-commonmark'
 import { factorySpace } from 'micromark-factory-space'
 import { prefixSize } from './utils'
diff --git a/src/micromark-extension/tokenize-container-suger.ts b/src/micromark-extension/tokenize-container-suger.ts
index 8ff6435..b6483f2 100644
--- a/src/micromark-extension/tokenize-container-suger.ts
+++ b/src/micromark-extension/tokenize-container-suger.ts
@@ -1,4 +1,4 @@
-import type { Effects, State, TokenizeContext, Code } from 'micromark-util-types'
+import type { Effects, State, TokenizeContext, Code } from './types'
 import { markdownLineEnding } from 'micromark-util-character'
 import { factorySpace } from 'micromark-factory-space'
 import componentContainer from './tokenize-inline'
diff --git a/src/micromark-extension/tokenize-container.ts b/src/micromark-extension/tokenize-container.ts
index 0d423c2..8911b08 100644
--- a/src/micromark-extension/tokenize-container.ts
+++ b/src/micromark-extension/tokenize-container.ts
@@ -1,4 +1,4 @@
-import type { Effects, State, Code, TokenizeContext } from 'micromark-util-types'
+import type { Effects, State, Code, TokenizeContext } from './types'
 import { factorySpace } from 'micromark-factory-space'
 import { markdownLineEnding, asciiAlpha, markdownSpace } from 'micromark-util-character'
 import { linePrefixSize, tokenizeCodeFence, useTokenState } from './utils'
@@ -33,7 +33,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
    */
   return start
 
-  function start (code: Code): State | void {
+  function start (code: Code): State | undefined {
     /* istanbul ignore if - handled by mm */
     if (code !== Codes.colon) { throw new Error('expected `:`') }
     effects.enter('componentContainer')
@@ -48,7 +48,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     let revertSectionState: () => void
     return closingPrefixAfter
 
-    function closingPrefixAfter (code: Code): State | void {
+    function closingPrefixAfter (code: Code): State | undefined {
       sectionIndentSize = linePrefixSize(self.events)
 
       // Close section
@@ -58,7 +58,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
       return closingSectionSequence(code)
     }
 
-    function closingSectionSequence (code: Code): State | void {
+    function closingSectionSequence (code: Code): State | undefined {
       if (code === slotSeparatorCode) {
         effects.consume(code)
         size++
@@ -88,7 +88,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     }
   }
 
-  function sectionOpen (code: Code): void | State {
+  function sectionOpen (code: Code): undefined | State {
     // Open new Section
     section.enter(effects)
 
@@ -100,7 +100,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return sectionTitle(code)
   }
 
-  function sectionTitle (code: Code): State | void {
+  function sectionTitle (code: Code): State | undefined {
     if (markdownLineEnding(code)) {
       effects.exit('componentContainerSectionTitle')
       return factorySpace(effects, lineStart, 'linePrefix', 4)(code)
@@ -109,7 +109,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return sectionTitle
   }
 
-  function sequenceOpen (code: Code): State | void {
+  function sequenceOpen (code: Code): State | undefined {
     if (code === Codes.colon) {
       effects.consume(code)
       sizeOpen++
@@ -124,23 +124,23 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return createName.call(self, effects, afterName, nok, 'componentContainerName')(code)
   }
 
-  function afterName (code: Code): State | void {
+  function afterName (code: Code): State | undefined {
     return code === Codes.openingSquareBracket
       ? effects.attempt(label, afterLabel, afterLabel)(code)
       : afterLabel(code)
   }
 
-  function afterLabel (code: Code): State | void {
+  function afterLabel (code: Code): State | undefined {
     return code === Codes.openingCurlyBracket
       ? effects.attempt(attributes, afterAttributes, afterAttributes)(code)
       : afterAttributes(code)
   }
 
-  function afterAttributes (code: Code): State | void {
+  function afterAttributes (code: Code): State | undefined {
     return factorySpace(effects, openAfter, 'whitespace')(code)
   }
 
-  function openAfter (code: Code): State | void {
+  function openAfter (code: Code): State | undefined {
     effects.exit('componentContainerFence')
 
     if (code === null) {
@@ -159,7 +159,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return nok(code)
   }
 
-  function contentStart (code: Code): State | void {
+  function contentStart (code: Code): State | undefined {
     if (code === null) {
       effects.exit('componentContainer')
       return ok(code)
@@ -173,7 +173,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return lineStart(code)
   }
 
-  function lineStartAfterPrefix (code: Code): State | void {
+  function lineStartAfterPrefix (code: Code): State | undefined {
     if (code === null) {
       return after(code)
     }
@@ -217,7 +217,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return chunkStart(code)
   }
 
-  function lineStart (code: Code): State | void {
+  function lineStart (code: Code): State | undefined {
     if (code === null) {
       return after(code)
     }
@@ -227,7 +227,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
       : lineStartAfterPrefix(code)
   }
 
-  function chunkStart (code: Code): State | void {
+  function chunkStart (code: Code): State | undefined {
     if (code === null) {
       return after(code)
     }
@@ -245,7 +245,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return contentContinue(code)
   }
 
-  function contentContinue (code: Code): State | void {
+  function contentContinue (code: Code): State | undefined {
     if (code === null) {
       effects.exit('chunkDocument')
       return after(code)
@@ -261,7 +261,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return contentContinue
   }
 
-  function after (code: Code): State | void {
+  function after (code: Code): State | undefined {
     // Close section
     section.exit(effects)
     effects.exit('componentContainerContent')
@@ -274,13 +274,13 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
 
     return factorySpace(effects, closingPrefixAfter, 'linePrefix', 4)
 
-    function closingPrefixAfter (code: Code): State | void {
+    function closingPrefixAfter (code: Code): State | undefined {
       effects.enter('componentContainerFence')
       effects.enter('componentContainerSequence')
       return closingSequence(code)
     }
 
-    function closingSequence (code: Code): State | void {
+    function closingSequence (code: Code): State | undefined {
       if (code === Codes.colon) {
         effects.consume(code)
         size++
@@ -300,7 +300,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
       return factorySpace(effects, closingSequenceEnd, 'whitespace')(code)
     }
 
-    function closingSequenceEnd (code: Code): State | void {
+    function closingSequenceEnd (code: Code): State | undefined {
       if (code === null || markdownLineEnding(code)) {
         effects.exit('componentContainerFence')
         return ok(code)
diff --git a/src/micromark-extension/tokenize-frontmatter.ts b/src/micromark-extension/tokenize-frontmatter.ts
index 09e3930..6a11100 100644
--- a/src/micromark-extension/tokenize-frontmatter.ts
+++ b/src/micromark-extension/tokenize-frontmatter.ts
@@ -1,4 +1,4 @@
-import type { Effects, State, TokenizeContext, Code } from 'micromark-util-types'
+import type { Effects, State, TokenizeContext, Code } from './types'
 import { factorySpace } from 'micromark-factory-space'
 import { markdownLineEnding, markdownSpace } from 'micromark-util-character'
 import { Codes, SectionSequenceSize } from './constants'
@@ -27,7 +27,7 @@ export function tokenizeFrontMatter (
 
     return closingPrefixAfter
 
-    function dataLineFirstSpaces (code: Code): State | void {
+    function dataLineFirstSpaces (code: Code): State | undefined {
       if (markdownSpace(code)) {
         effects.consume(code)
         sectionIndentSize += 1
@@ -37,7 +37,7 @@ export function tokenizeFrontMatter (
       return closingPrefixAfter(code)
     }
 
-    function closingPrefixAfter (code: Code): State | void {
+    function closingPrefixAfter (code: Code): State | undefined {
       if (markdownSpace(code)) {
         effects.enter('space')
         return dataLineFirstSpaces(code)
@@ -49,7 +49,7 @@ export function tokenizeFrontMatter (
       return closingSectionSequence(code)
     }
 
-    function closingSectionSequence (code: Code): State | void {
+    function closingSectionSequence (code: Code): State | undefined {
       if (code === Codes.dash || markdownSpace(code)) {
         effects.consume(code)
         size++
@@ -69,7 +69,7 @@ export function tokenizeFrontMatter (
   /**
    * Enter data section
    */
-  function dataSectionOpen (code: Code): State | void {
+  function dataSectionOpen (code: Code): State | undefined {
     effects.enter('componentContainerDataSection')
     return effects.attempt({
       tokenize: tokenizeDataSection as any,
@@ -80,7 +80,7 @@ export function tokenizeFrontMatter (
   /**
    *  Data section line
    */
-  function dataChunkStart (code: Code): State | void {
+  function dataChunkStart (code: Code): State | undefined {
     if (code === null) {
       effects.exit('componentContainerDataSection')
       effects.exit('componentContainer')
@@ -100,7 +100,7 @@ export function tokenizeFrontMatter (
   /**
    * Data section content
    */
-  function dataContentContinue (code: Code): State | void {
+  function dataContentContinue (code: Code): State | undefined {
     if (code === null) {
       effects.exit('chunkDocument')
       effects.exit('componentContainerDataSection')
@@ -124,7 +124,7 @@ export function tokenizeFrontMatter (
   /**
    * Exit data section
    */
-  function dataSectionClose (code: Code): State | void {
+  function dataSectionClose (code: Code): State | undefined {
     effects.exit('componentContainerDataSection')
     return factorySpace(effects, next, 'whitespace')(code)
   }
diff --git a/src/micromark-extension/tokenize-span.ts b/src/micromark-extension/tokenize-span.ts
index 1f3035c..3288c13 100644
--- a/src/micromark-extension/tokenize-span.ts
+++ b/src/micromark-extension/tokenize-span.ts
@@ -15,7 +15,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
 
   return start
 
-  function start (code: Code): void | State {
+  function start (code: Code): State | undefined {
     if (code !== Codes.openingSquareBracket) {
       throw new Error('expected `[`')
     }
@@ -36,12 +36,12 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return effects.check(doubleBracketCheck, nok, attemptLabel)(code)
   }
 
-  function attemptLabel (code: Code): void | State {
+  function attemptLabel (code: Code): State | undefined {
     effects.enter('textSpan')
     return effects.attempt(label, exit as State, nok)(code)
   }
 
-  function exit (code: Code): void | State {
+  function exit (code: Code): State | undefined {
     // Prevent conflict with link syntax
     if (code === Codes.openingParentheses || code === Codes.openingSquareBracket) {
       return nok(code)
@@ -54,7 +54,7 @@ function tokenize (this: TokenizeContext, effects: Effects, ok: State, nok: Stat
     return exitOK(code)
   }
 
-  function exitOK (code: Code): void | State {
+  function exitOK (code: Code): State | undefined {
     effects.exit('textSpan')
     return ok(code)
   }
@@ -74,13 +74,13 @@ export default {
 function checkGfmTaskCheckbox (effects: Effects, ok: State, nok: State) {
   return enter
 
-  function enter (code: Code): void | State {
+  function enter (code: Code): State | undefined {
     effects.enter('formGfmTaskCheckbox')
     effects.consume(code)
     return check
   }
 
-  function check (code: Code): void | State {
+  function check (code: Code): State | undefined {
     if (markdownSpace(code)) {
       effects.consume(code)
       return check
@@ -102,13 +102,13 @@ function checkGfmTaskCheckbox (effects: Effects, ok: State, nok: State) {
 function checkDoubleBracket (effects: Effects, ok: State, nok: State) {
   return enter
 
-  function enter (code: Code): void | State {
+  function enter (code: Code): State | undefined {
     effects.enter('doubleBracket')
     effects.consume(code)
     return check
   }
 
-  function check (code: Code): void | State {
+  function check (code: Code): State | undefined {
     if (code !== Codes.openingSquareBracket) {
       return nok(code)
     }
diff --git a/src/micromark-extension/types.ts b/src/micromark-extension/types.ts
new file mode 100644
index 0000000..587a840
--- /dev/null
+++ b/src/micromark-extension/types.ts
@@ -0,0 +1,64 @@
+export type { Effects, State, Code, TokenizeContext, TokenTypeMap } from 'micromark-util-types'
+
+declare module 'micromark-util-types' {
+  interface TokenTypeMap {
+    componentContainer: 'componentContainer',
+    componentContainerName: 'componentContainerName',
+    componentContainerFence: 'componentContainerFence',
+    componentContainerSequence: 'componentContainerSequence',
+    componentContainerSection: 'componentContainerSection',
+    componentContainerSectionSequence: 'componentContainerSectionSequence',
+    componentContainerSectionTitle: 'componentContainerSectionTitle',
+    componentContainerContent: 'componentContainerContent',
+
+    componentContainerLabel: 'componentContainerLabel',
+    componentContainerLabelMarker: 'componentContainerLabelMarker',
+    componentContainerLabelString: 'componentContainerLabelString',
+
+    componentContainerDataSection: 'componentContainerDataSection',
+
+    componentContainerAttributes: 'componentContainerAttributes',
+    componentContainerAttributesMarker: 'componentContainerAttributesMarker',
+    componentContainerAttribute: 'componentContainerAttribute',
+    componentContainerAttributeId: 'componentContainerAttributeId',
+    componentContainerAttributeClass: 'componentContainerAttributeClass',
+    componentContainerAttributeName: 'componentContainerAttributeName',
+    componentContainerAttributeInitializerMarker: 'componentContainerAttributeInitializerMarker',
+    componentContainerAttributeValueLiteral: 'componentContainerAttributeValueLiteral',
+    componentContainerAttributeValue: 'componentContainerAttributeValue',
+    componentContainerAttributeValueMarker: 'componentContainerAttributeValueMarker',
+    componentContainerAttributeValueData: 'componentContainerAttributeValueData',
+
+    bindingContent: 'bindingContent',
+    bindingFence: 'bindingFence',
+
+    
+
+    // Component Text
+    componentText: 'componentText',
+    componentTextMarker: 'componentTextMarker',
+    componentTextName: 'componentTextName',
+    componentTextLabel: 'componentTextLabel',
+    componentTextLabelMarker: 'componentTextLabelMarker',
+    componentTextLabelString: 'componentTextLabelString',
+
+    componentTextAttributes: 'componentTextAttributes',
+    componentTextAttributesMarker: 'componentTextAttributesMarker',
+    componentTextAttribute: 'componentTextAttribute',
+    componentTextAttributeId: 'componentTextAttributeId',
+    componentTextAttributeClass: 'componentTextAttributeClass',
+    componentTextAttributeName: 'componentTextAttributeName',
+    componentTextAttributeInitializerMarker: 'componentTextAttributeInitializerMarker',
+    componentTextAttributeValueLiteral: 'componentTextAttributeValueLiteral',
+    componentTextAttributeValue: 'componentTextAttributeValue',
+    componentTextAttributeValueMarker: 'componentTextAttributeValueMarker',
+    componentTextAttributeValueData: 'componentTextAttributeValueData',
+
+    // Text Span
+    textSpan: 'textSpan',
+
+    // Others
+    formGfmTaskCheckbox: 'formGfmTaskCheckbox'
+    doubleBracket: 'doubleBracket'
+  }
+}
\ No newline at end of file
diff --git a/src/micromark-extension/utils.ts b/src/micromark-extension/utils.ts
index d4e5c3d..657e463 100644
--- a/src/micromark-extension/utils.ts
+++ b/src/micromark-extension/utils.ts
@@ -1,4 +1,4 @@
-import type { Effects, State, Code } from 'micromark-util-types'
+import type { Effects, State, Code, TokenTypeMap } from './types'
 import { Codes } from './constants'
 
 // Measure the number of character codes in chunks.
@@ -41,7 +41,7 @@ export function linePrefixSize (events: any[]) {
 /**
  * Manage token state
  */
-export const useTokenState = (tokenName: string) => {
+export const useTokenState = (tokenName: keyof TokenTypeMap) => {
   const token = {
     isOpen: false,
     /**
@@ -99,12 +99,12 @@ function checkCodeFenced (effects: Effects, ok: State, nok: State) {
 
   return start
 
-  function start (code: Code): State | void {
+  function start (code: Code): State | undefined {
     effects.enter('codeFenced')
     return after(code)
   }
 
-  function after (code: Code): State | void {
+  function after (code: Code): State | undefined {
     if (code === Codes.backTick) {
       backTickCount++
       effects.consume(code)