diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5a88faf..eb4c24e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+#### Fixed
+- Some abstract methods were not implemented from interfaces
+- Optional parameters are implemented now ([#141](https://github.com/buehler/typescript-hero/issues/141))
+
 #### Removed
 - The document view, since there is a command `cmd+shift+o` that basically does the same, but better
 
diff --git a/src/common/ts-parsing/declarations/MethodDeclaration.ts b/src/common/ts-parsing/declarations/MethodDeclaration.ts
index 341772f..c87e96e 100644
--- a/src/common/ts-parsing/declarations/MethodDeclaration.ts
+++ b/src/common/ts-parsing/declarations/MethodDeclaration.ts
@@ -18,7 +18,7 @@ import { CompletionItemKind } from 'vscode-languageserver-types';
  */
 @Serializable({
     factory: (json) => {
-        const obj = new MethodDeclaration(json.name, json.isExported, json.visibility, json.type, json.start, json.end);
+        const obj = new MethodDeclaration(json.name, json.isAbstract, json.visibility, json.type, json.start, json.end);
         obj.parameters = json.parameters;
         obj.variables = json.variables;
         return obj;
diff --git a/test/_workspace/extension/extensions/codeActionExtension/implementInterfaceOrAbstract.ts b/test/_workspace/extension/extensions/codeActionExtension/implementInterfaceOrAbstract.ts
index a40e725..33bf0f8 100644
--- a/test/_workspace/extension/extensions/codeActionExtension/implementInterfaceOrAbstract.ts
+++ b/test/_workspace/extension/extensions/codeActionExtension/implementInterfaceOrAbstract.ts
@@ -29,7 +29,7 @@ interface GenericInterface<T1, T2> {
 
 abstract class GenericAbstractClass<T1, T2, T3> {
     public abstract abstractMethod(p1: T1): T2;
-    protected abstract protMethod(p2: T2, p3: T3);
+    protected abstract protMethod(p2: T2, p3?: T3);
 }
 
 class ImplementGenericInterface implements GenericInterface<string, number> {