diff --git a/.changeset/brave-mirrors-rhyme.md b/.changeset/brave-mirrors-rhyme.md
new file mode 100644
index 0000000..75b8f66
--- /dev/null
+++ b/.changeset/brave-mirrors-rhyme.md
@@ -0,0 +1,5 @@
+---
+'@difizen/mana-core': patch
+---
+
+fix(core): the `update` method of the theme is defined using an arrow function.
diff --git a/packages/mana-core/src/theme/theme-app.ts b/packages/mana-core/src/theme/theme-app.ts
index b1b449b..3e8acb2 100644
--- a/packages/mana-core/src/theme/theme-app.ts
+++ b/packages/mana-core/src/theme/theme-app.ts
@@ -66,7 +66,7 @@ export class ThemeApplication implements ApplicationContribution {
       this.toUpdate.push(Disposable.create(() => host.classList.remove(themeClass)));
     }
   }
-  protected update(): void {
+  protected update = (): void => {
     this.toUpdate.dispose();
     this.toUpdate = new DisposableCollection();
     this.setThemeClassName();
@@ -76,5 +76,5 @@ export class ThemeApplication implements ApplicationContribution {
     ]) {
       this.setCssVariable(cv);
     }
-  }
+  };
 }