diff --git a/packages/compiler-sfc/__tests__/compileScript/resolveType.spec.ts b/packages/compiler-sfc/__tests__/compileScript/resolveType.spec.ts
index b7056a68815..9bbad1dda61 100644
--- a/packages/compiler-sfc/__tests__/compileScript/resolveType.spec.ts
+++ b/packages/compiler-sfc/__tests__/compileScript/resolveType.spec.ts
@@ -535,6 +535,21 @@ describe('resolveType', () => {
     })
   })
 
+  test('keyof: fallback to UNKNOWN', () => {
+    const { props } = resolve(
+      `
+      interface Barr {}
+      interface Bar extends Barr {}
+      type Foo = keyof Bar
+      defineProps<{ foo: Foo }>()
+      `,
+    )
+
+    expect(props).toStrictEqual({
+      foo: ['UNKNOWN'],
+    })
+  })
+
   test('ExtractPropTypes (element-plus)', () => {
     const { props, raw } = resolve(
       `
diff --git a/packages/compiler-sfc/src/script/resolveType.ts b/packages/compiler-sfc/src/script/resolveType.ts
index 0ebf376e17c..e269c217e62 100644
--- a/packages/compiler-sfc/src/script/resolveType.ts
+++ b/packages/compiler-sfc/src/script/resolveType.ts
@@ -1496,7 +1496,7 @@ export function inferRuntimeType(
           }
         }
 
-        return types.size ? Array.from(types) : ['Object']
+        return types.size ? Array.from(types) : [isKeyOf ? 'UNKNOWN' : 'Object']
       }
       case 'TSPropertySignature':
         if (node.typeAnnotation) {