diff --git a/types/plist/index.d.ts b/types/plist/index.d.ts
index b7064e55a3..f97b267df4 100644
--- a/types/plist/index.d.ts
+++ b/types/plist/index.d.ts
@@ -20,9 +20,9 @@ export type PlistValue =
   string | number | boolean |
   Date | Buffer | PlistObject | PlistArray;
 export interface PlistObject {
-  [x: string]: PlistValue;
+  readonly [x: string]: PlistValue;
 }
-export interface PlistArray extends Array<PlistValue> { }
+export interface PlistArray extends ReadonlyArray<PlistValue> { }
 
 // PlistBuildOptions
 // The instance of this type is passed to 'xmlbuilder' module as it is.
diff --git a/types/plist/plist-tests.ts b/types/plist/plist-tests.ts
index a94cb4cf71..00dc33b56c 100644
--- a/types/plist/plist-tests.ts
+++ b/types/plist/plist-tests.ts
@@ -79,3 +79,10 @@ console.log(plistString1);
 
 const plistString2 = plist.build(plistValue2, {pretty: false});
 console.log(plistString2);
+
+function f(a: ReadonlyArray<string>) {
+    plist.build(a);
+}
+
+// $ExpectError
+plist.build(() => 0);