diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7228e648..d4f02c02 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Fixed
+
+- definitions: appendPage optionnal parameter
+
 ## [4.0.0] - 2023-07-14
 
 ### Fixed
diff --git a/muhammara.d.ts b/muhammara.d.ts
index 8253e10a..aaced64e 100755
--- a/muhammara.d.ts
+++ b/muhammara.d.ts
@@ -1025,7 +1025,7 @@ declare module "muhammara" {
       options?: Recipe.AnnotOptions
     ): Recipe;
 
-    appendPage(pdfSrc: string, pages: number | number[]): Recipe;
+    appendPage(pdfSrc: string, pages?: number | number[]): Recipe;
 
     encrypt(options: Recipe.EncryptOptions): Recipe;