diff --git a/src/mount.ts b/src/mount.ts
index 1adc7588e..0046c461e 100644
--- a/src/mount.ts
+++ b/src/mount.ts
@@ -24,7 +24,7 @@ export type ComponentMountingOptions<
   P extends ComponentProps<T> = ComponentProps<T>
 > = Omit<MountingOptions<P, ComponentData<T>>, 'slots'> & {
   slots?: {
-    [K in keyof ComponentSlots<T>]: WithArray<
+    [K in keyof ComponentSlots<T>]?: WithArray<
       | ShimSlotReturnType<ComponentSlots<T>[K]>
       | string
       | VNode
diff --git a/test-dts/mount.d-test.ts b/test-dts/mount.d-test.ts
index feadf91f4..7996fd56a 100644
--- a/test-dts/mount.d-test.ts
+++ b/test-dts/mount.d-test.ts
@@ -9,7 +9,9 @@ import {
   ref,
   SetupContext,
   Prop,
-  VNodeChild
+  VNodeChild,
+  SlotsType,
+  VNode
 } from 'vue'
 import { Options, Vue } from 'vue-class-component'
 import { mount } from '../src'
@@ -340,3 +342,82 @@ expectError(
     }
   )
 )
+
+// slots
+const SetupComponentWithSlots = defineComponent<
+  {
+    hello: string
+  },
+  {
+    hallo: () => void
+  },
+  string,
+  SlotsType<{
+    foo: () => VNode[]
+    bar: () => VNode[]
+    baz: () => VNode[]
+  }>
+>((): any => {})
+
+// optional slots
+mount(SetupComponentWithSlots, {})
+
+mount(SetupComponentWithSlots, {
+  slots: {}
+})
+
+mount(SetupComponentWithSlots, {
+  slots: {
+    foo: 'foo'
+  }
+})
+
+mount(SetupComponentWithSlots, {
+  slots: {
+    foo: 'foo',
+    bar: 'bar'
+  }
+})
+
+mount(SetupComponentWithSlots, {
+  slots: {
+    foo: 'foo',
+    bar: 'bar',
+    baz: 'baz'
+  }
+})
+
+// extra slots
+mount(SetupComponentWithSlots, {
+  slots: {
+    // @ts-expect-error - This slot doesn't exist in the component and it should be reported.
+    extraSlot: 'nonExistentSlot'
+  }
+})
+
+mount(SetupComponentWithSlots, {
+  slots: {
+    foo: 'foo',
+    // @ts-expect-error - This slot doesn't exist in the component and it should be reported.
+    extraSlot: 'nonExistentSlot'
+  }
+})
+
+mount(SetupComponentWithSlots, {
+  slots: {
+    foo: 'foo',
+    bar: 'bar',
+    // @ts-expect-error - This slot doesn't exist in the component and it should be reported.
+    extraSlot: 'nonExistentSlot'
+  }
+})
+
+mount(SetupComponentWithSlots, {
+  slots: {
+    foo: 'foo',
+    bar: 'bar',
+    baz: 'baz',
+    // @ts-expect-error - This slot doesn't exist in the component and it should be reported.
+    extraSlot: 'nonExistentSlot'
+  }
+})
diff --git a/test-dts/tsconfig.tsd.json b/test-dts/tsconfig.tsd.json
index f10ca8eb3..536ae6ded 100644
--- a/test-dts/tsconfig.tsd.json
+++ b/test-dts/tsconfig.tsd.json
@@ -4,6 +4,7 @@
     "noEmit": false,
     "skipLibCheck": true,
     "experimentalDecorators": true,
+    "noUncheckedIndexedAccess": true,
     "strictNullChecks": false
   },
   "exclude": [