diff --git a/dist/index.d.ts b/dist/index.d.ts
index 5cf4165..6790ba1 100644
--- a/dist/index.d.ts
+++ b/dist/index.d.ts
@@ -53,7 +53,7 @@ export declare type Options = {
  * @param options - Options for the function.
  * @returns An array of similar words.
  */
-export declare function findSimilar(word: string, candidates: string[], options?: Options): string[];
+export declare function findSimilar(word: string, candidates: readonly string[] | string[], options?: Options): string[];
 /**
  * Suggests similar words in a list of words.
  *
@@ -62,4 +62,4 @@ export declare function findSimilar(word: string, candidates: string[], options?
  * @param options - Options for the function.
  * @returns A string of suggested words.
  */
-export declare function didYouMean(word: string, candidates: string[], options?: Options): string;
+export declare function didYouMean(word: string, candidates: readonly string[] | string[], options?: Options): string;
diff --git a/src/index.ts b/src/index.ts
index 33be1a7..a4e4134 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -61,7 +61,7 @@ export type Options = {
  */
 export function findSimilar(
   word: string,
-  candidates: string[],
+  candidates: readonly string[] | string[],
   options: Options = {}
 ) {
   let { maxScore = 3 } = options
@@ -96,7 +96,7 @@ export function findSimilar(
  */
 export function didYouMean(
   word: string,
-  candidates: string[],
+  candidates: readonly string[] | string[],
   options: Options = {}
 ) {
   const matches = findSimilar(word, candidates, options)