How to change Toolbar home icon color

I am using a android.support.v7.widget.Toolbar and learned from this post how to change the color of the hamburger icon to white, but the up/back arrow remains a dark color when I call

setDisplayHomeAsUpEnabled(true);

How can I make the arrow white as well?

Here is what my toolbar looks like when I call setDisplayHomeAsUpEnabled():

...and here is the relevant portion of my styles.xml file:

<style name="AppTheme" parent="Theme.AppCompat.NoActionBar">
    <item name="colorPrimary">@color/primary</item>
    <item name="colorPrimaryDark">#194C5F</item>
    <item name="colorAccent">@color/accent</item>
    <item name="drawerArrowStyle">@style/WhiteDrawerIconStyle</item>
</style>

    <style name="WhiteDrawerIconStyle" parent="Widget.AppCompat.DrawerArrowToggle">
        <item name="spinBars">true</item>
        <item name="color">@android:color/white</item>
    </style>

I solved it by editing styles.xml:

<style name="ToolbarColoredBackArrow" parent="AppTheme">
    <item name="android:textColorSecondary">INSERT_COLOR_HERE</item>
</style>

...then referencing the style in the Toolbar definition in the activity:

<LinearLayout
    android:id="@+id/main_parent_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <android.support.v7.widget.Toolbar
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/toolbar"
        app:theme="@style/ToolbarColoredBackArrow"
        app:popupTheme="@style/AppTheme"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:minHeight="?attr/actionBarSize"
        android:background="?attr/colorPrimary"/>