WebStorm: Angular Material HTML tags shown as an "unknown element" but compiles and works fine

Question

I am currently using Angular 2 Material Design for a very small project. To enable the modules I need, I created MaterialModule:

import { NgModule } from '@angular/core';

import {
  MatButtonModule,
  MatMenuModule,
  MatToolbarModule,
  MatIconModule,
  MatCardModule
} from '@angular/material';

@NgModule({
  imports: [
    MatButtonModule,
    MatMenuModule,
    MatToolbarModule,
    MatIconModule,
    MatCardModule
  ],
  exports: [
    MatButtonModule,
    MatMenuModule,
    MatToolbarModule,
    MatIconModule,
    MatCardModule
  ]
})
export class MaterialModule {}

I have imported this module into my class AppModule. Now when I try to use the HTML tags provided by the Material Design modules, WebStorm gives me this error:

Angular: "mat-toolbar" : 1. " " Angular, , . 2. " " -, "CUSTOM_ELEMENTS_SCHEMA" '@NgModule.schemas' .

, , .

, , .

- / MaterialModule, Angular, WebStorm ?