diff --git a/.changeset/readonly-detect-order.md b/.changeset/readonly-detect-order.md
new file mode 100644
index 0000000..7899f80
--- /dev/null
+++ b/.changeset/readonly-detect-order.md
@@ -0,0 +1,5 @@
+---
+"@changesets/format": patch
+---
+
+Accept readonly arrays in the `order` option of `detect`.
diff --git a/src/detect.ts b/src/detect.ts
index a302e21..25d9f59 100644
--- a/src/detect.ts
+++ b/src/detect.ts
@@ -25,7 +25,7 @@ export interface DetectOptions {
    * The order of formatters to check for.
    * @default ["dprint", "deno", "oxfmt", "biome", "prettier"] // from `defaultDetectOrder`
    */
-  order?: FormatterName[];
+  order?: readonly FormatterName[];
 }
 
 /**