Laravel Migration Foreign key constraint is incorrectly formed

when migrating my db this error appears ,below this my code followed by the error

 public function up()
    {
        Schema::create('meals', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('user_id')->unsigned();
            $table->integer('category_id')->unsigned();
            $table->string('title');
            $table->string('body');
            $table->string('meal_av');
            $table->timestamps();

            $table->foreign('user_id')
                ->references('id')
                ->on('users')
                ->onDelete('cascade');

            $table->foreign('category_id')
                ->references('id')
                ->on('categories')
                ->onDelete('cascade');
        });
    }  

[Illuminate\Database\QueryException]
SQLSTATE[HY000]: General error: 1005 Can't create table meal.#sql-11d2_1
4 (errno: 150 "Foreign key constraint is incorrectly formed") (SQL: alter
table meals add constraint meals_category_id_foreign foreign key (catego
ry_id) references categories (id) on delete cascade)

via Chebli Mohamed