diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index eb9b79f5..0cbc5b8e 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -68,10 +68,10 @@ export type PropInputType = 'array' | 'object' | 'stringEnum' | 'primitiveArray'
 
 type StringLiteral<T> = T extends string ? (string extends T ? never : T) : never
 type FilterStringLiteral<T> = {
-  [K in keyof T]: T[K] extends StringLiteral<T[K]> ? K : never;
+  [K in keyof T]-?: NonNullable<T[K]> extends StringLiteral<NonNullable<T[K]>> ? K : never
 }[keyof T]
 
-type ComboItem<T> = keyof FilterStringLiteral<T> | undefined
+type ComboItem<T> = FilterStringLiteral<T> | undefined
 type Combo<T> = [ComboItem<T>, ComboItem<T>] | [ComboItem<T>]
 
 export type ComponentsDir = {
diff --git a/playgrounds/vue/src/components/SupportedProps.vue b/playgrounds/vue/src/components/SupportedProps.vue
index be110040..3b4dd823 100644
--- a/playgrounds/vue/src/components/SupportedProps.vue
+++ b/playgrounds/vue/src/components/SupportedProps.vue
@@ -5,6 +5,8 @@ const _props = defineProps<{
   number?: number
   boolean?: boolean
   primitiveUnion?: string | number | boolean
+  requiredStringLiteral: 'primary' | 'secondary'
+  optionalStringLiteral?: 'small' | 'large'
 
   // Arrays
   stringArray?: string[]
@@ -33,6 +35,7 @@ const _props = defineProps<{
 }>()
 
 extendCompodiumMeta<typeof _props>({
+  combo: ['requiredStringLiteral', 'optionalStringLiteral'],
   defaultProps: {
     string: 'hello',
     primitiveUnion: 42,