Vue-multiselect conflict with input groups

HTML

<link rel="stylesheet" href="https://unpkg.com/vue-multiselect@2.0.2/dist/vue-multiselect.min.css">
<script src="https://unpkg.com/vue-multiselect@2.0.2/dist/vue-multiselect.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<div id="app">
  <label for="">Select</label>
  <div>
  <multiselect v-model="value" :options="options" :multiple="true">
  </multiselect>  
  </div>

  <label for="">Input</label>
  <div class="input-group">
    <input type="text" class="form-control index-fix" placeholder="Search for...">
    <span class="input-group-btn">
      <button class="btn btn-default" type="button">Go!</button>
    </span>
  </div>
  <!-- /input-group -->
</div>

CSS

* {
  font-family: 'Lato', 'Avenir', sans-serif;
}

.multiselect--active {
  z-index: 1000;
}

Babel + JSX

new Vue({
	components: {
  	Multiselect: window.VueMultiselect.default
	},
	data: {
  	value: null,
  	options: [ 'lorem', 'ipsum', 'dolor' ]
	}
}).$mount('#app')