diff --git a/src/__tests__/attributes.test.ts b/src/__tests__/attributes.test.ts
index 1fb664d..3d66c0b 100644
--- a/src/__tests__/attributes.test.ts
+++ b/src/__tests__/attributes.test.ts
@@ -34,4 +34,12 @@ describe('attributes.ts', () => {
 
     expect(el.value).toBe('test');
   });
+
+  test("doesn't add `mounted` as an attribute", () => {
+    const el = document.createElement('div');
+
+    addAttribute(el, 'mounted', 'test');
+
+    expect(el.hasAttribute('mounted')).toBe(false);
+  });
 });
diff --git a/src/__tests__/main.test.ts b/src/__tests__/main.test.ts
deleted file mode 100644
index 8c2109b..0000000
--- a/src/__tests__/main.test.ts
+++ /dev/null
@@ -1,32 +0,0 @@
-import { Component, mount, tags } from '../main';
-
-describe('main', () => {
-  test('`null` element', () => {
-    const el = document.querySelector('.not-defined');
-
-    expect(mount(el, {} as Component)).toBe(undefined);
-  });
-
-  test('setting an unknown state property', () => {
-    const el = document.createElement('div');
-
-    expect(() =>
-      mount(el, {
-        state: { count: 0 },
-        view: ({ state }) =>
-          tags.div('', { mounted: () => state['unknown']++ }),
-      }),
-    ).toThrow();
-  });
-
-  test('setting a state property to the same value', () => {
-    const el = document.createElement('div');
-
-    expect(() =>
-      mount(el, {
-        state: { count: 0 },
-        view: ({ state }) => tags.div('', { mounted: () => (state.count = 0) }),
-      }),
-    ).not.toThrow();
-  });
-});
diff --git a/src/__tests__/tags.test.ts b/src/__tests__/tags.test.ts
index ce810ab..89ef009 100644
--- a/src/__tests__/tags.test.ts
+++ b/src/__tests__/tags.test.ts
@@ -68,4 +68,12 @@ describe('tags.ts', () => {
     expect(el.$tent.attributes['data-bar']).toBe('baz');
     expect(el.$tent.attributes['onclick']).toBe(fn);
   });
+
+  test('mounted', () => {
+    const fn = jest.fn();
+    const el = createTag(['div', 'test', { mounted: fn }]);
+
+    expect(fn).toHaveBeenCalledTimes(1);
+    expect(fn).toHaveBeenCalledWith({ el });
+  });
 });
diff --git a/src/attributes.ts b/src/attributes.ts
index 1529e2e..bafe1db 100644
--- a/src/attributes.ts
+++ b/src/attributes.ts
@@ -1,10 +1,14 @@
-import { type TentNode, type Attrs } from './types';
+import { type TentNode, type Attrs, type TagAttrsValues } from './types';
 
 function addAttribute<A extends Attrs>(
   el: TentNode<A> | HTMLElement,
   key: string,
-  value: string | boolean | number,
+  value: TagAttrsValues,
 ) {
+  if (key === 'mounted') {
+    return;
+  }
+
   if (typeof value === 'boolean') {
     if (value) {
       el.setAttribute(key, '');
diff --git a/src/tags.ts b/src/tags.ts
index 0edfee3..c8ca138 100644
--- a/src/tags.ts
+++ b/src/tags.ts
@@ -26,6 +26,8 @@ function createTag(context: Context) {
     el.append(typeof children === 'number' ? children.toString() : children);
   }
 
+  attributes?.mounted?.({ el });
+
   return el;
 }
 
diff --git a/src/types.ts b/src/types.ts
index fc6e146..c16b87d 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -23,9 +23,13 @@ export type TentNode<A extends Attrs = undefined> = Node &
   };
 
 export type Children = string | number | TentNode | (Node | string | Context)[];
-export type Context = [string, Children, object | undefined];
+export type Context = [string, Children, TagAttrs | undefined];
 
+export type TagAttrsValues = string | boolean | number | Function;
+type TagAttrs = Record<string, TagAttrsValues> & {
+  mounted?: ({ el }: { el: TentNode }) => void;
+};
 export type Tags = Record<
   string,
-  (children: Children, attrs?: object) => TentNode
+  (children: Children, attrs?: TagAttrs) => TentNode
 >;
diff --git a/src/walker.ts b/src/walker.ts
index a68a739..fc3dd29 100644
--- a/src/walker.ts
+++ b/src/walker.ts
@@ -19,6 +19,12 @@ function walker<A extends Attrs>(oldNode: TentNode<A>, newNode: TentNode<A>) {
     return;
   }
 
+  if (oldNode.$tent == null || newNode.$tent == null) {
+    oldNode.replaceWith(newNode);
+
+    return;
+  }
+
   // Remove attributes that are not present in the new node
   for (const key in oldNode.$tent.attributes) {
     if (newNode.$tent.attributes[key] == null) {