diff --git a/README.md b/README.md
index c8ef5cf..86a4e32 100644
--- a/README.md
+++ b/README.md
@@ -72,7 +72,7 @@ function toRegExp(
 type OnigurumaToEsOptions = {
   accuracy?: 'strict' | 'default' | 'loose';
   avoidSubclass?: boolean;
-  flags?: OnigurumaFlags;
+  flags?: string;
   global?: boolean;
   hasIndices?: boolean;
   maxRecursionDepth?: number | null;
@@ -111,7 +111,7 @@ Returns an Oniguruma AST generated from an Oniguruma pattern.
 function toOnigurumaAst(
   pattern: string,
   options?: {
-    flags?: OnigurumaFlags;
+    flags?: string;
   }
 ): OnigurumaAst;
 ```
diff --git a/scripts/onig-match.js b/scripts/onig-match.js
index 7322314..108e6b5 100644
--- a/scripts/onig-match.js
+++ b/scripts/onig-match.js
@@ -1,5 +1,10 @@
 import {areMatchDetailsEqual, color, cp, err, ok, onigurumaResult, r, transpiledRegExpResult, value} from './utils.js';
 
+// To run this script:
+// - npm run onig:match '\w' 'a'
+// - npm run onig:match '\n' '\u{A}'
+// Don't use pnpm because it auto-escapes backslashes in string args
+
 exec(process.argv.slice(2));
 
 // Basic Oniguruma tester for the console; also reports a comparison with Oniguruma-to-ES
diff --git a/src/index.js b/src/index.js
index ee06b6b..c14b876 100644
--- a/src/index.js
+++ b/src/index.js
@@ -24,7 +24,7 @@ import {recursion} from 'regex-recursion';
 @typedef {{
   accuracy?: keyof Accuracy;
   avoidSubclass?: boolean;
-  flags?: import('./tokenize.js').OnigurumaFlags;
+  flags?: string;
   global?: boolean;
   hasIndices?: boolean;
   maxRecursionDepth?: number | null;
@@ -78,7 +78,7 @@ function toDetails(pattern, options) {
 Returns an Oniguruma AST generated from an Oniguruma pattern.
 @param {string} pattern Oniguruma regex pattern.
 @param {{
-  flags?: import('./tokenize.js').OnigurumaFlags;
+  flags?: string;
 }} [options]
 @returns {import('./parse.js').OnigurumaAst}
 */
diff --git a/src/tokenize.js b/src/tokenize.js
index 9b32108..9f69ec6 100644
--- a/src/tokenize.js
+++ b/src/tokenize.js
@@ -113,10 +113,6 @@ const charClassTokenRe = new RegExp(r`
 `.replace(/\s+/g, ''), 'gsu');
 
 /**
-@typedef {'i' | ''} FlagI
-@typedef {'m' | ''} FlagM
-@typedef {'x' | ''} FlagX
-@typedef {`${FlagI}${FlagM}${FlagX}` | `${FlagI}${FlagX}${FlagM}` | `${FlagM}${FlagI}${FlagX}` | `${FlagM}${FlagX}${FlagI}` | `${FlagX}${FlagI}${FlagM}` | `${FlagX}${FlagM}${FlagI}`} OnigurumaFlags
 @typedef {{
   type: keyof TokenTypes;
   raw: string;
@@ -133,7 +129,7 @@ const charClassTokenRe = new RegExp(r`
 */
 /**
 @param {string} pattern
-@param {OnigurumaFlags} [flags] Oniguruma flags. Flag `m` is equivalent to JS flag `s`.
+@param {string} [flags] Oniguruma flags. Flag `m` is equivalent to JS flag `s`.
 @returns {TokenizerResult}
 */
 function tokenize(pattern, flags = '') {