diff --git a/wp-includes/class-wp-customize-panel.php b/wp-includes/class-wp-customize-panel.php
index 3f5a4a3566..a3f02b2f67 100644
--- a/wp-includes/class-wp-customize-panel.php
+++ b/wp-includes/class-wp-customize-panel.php
@@ -384,101 +384,5 @@ class WP_Customize_Panel {
 	}
 }
 
-/**
- * Customize Nav Menus Panel Class
- *
- * Needed to add screen options.
- *
- * @since 4.3.0
- *
- * @see WP_Customize_Panel
- */
-class WP_Customize_Nav_Menus_Panel extends WP_Customize_Panel {
-
-	/**
-	 * Control type.
-	 *
-	 * @since 4.3.0
-	 * @access public
-	 * @var string
-	 */
-	public $type = 'nav_menus';
-
-	/**
-	 * Render screen options for Menus.
-	 *
-	 * @since 4.3.0
-	 * @access public
-	 */
-	public function render_screen_options() {
-		// Essentially adds the screen options.
-		add_filter( 'manage_nav-menus_columns', array( $this, 'wp_nav_menu_manage_columns' ) );
-
-		// Display screen options.
-		$screen = WP_Screen::get( 'nav-menus.php' );
-		$screen->render_screen_options( array( 'wrap' => false ) );
-	}
-
-	/**
-	 * Returns the advanced options for the nav menus page.
-	 *
-	 * Link title attribute added as it's a relatively advanced concept for new users.
-	 *
-	 * @since 4.3.0
-	 * @access public
-	 *
-	 * @return array The advanced menu properties.
-	 */
-	public function wp_nav_menu_manage_columns() {
-		return array(
-			'_title'      => __( 'Show advanced menu properties' ),
-			'cb'          => '<input type="checkbox" />',
-			'link-target' => __( 'Link Target' ),
-			'attr-title'  => __( 'Title Attribute' ),
-			'css-classes' => __( 'CSS Classes' ),
-			'xfn'         => __( 'Link Relationship (XFN)' ),
-			'description' => __( 'Description' ),
-		);
-	}
-
-	/**
-	 * An Underscore (JS) template for this panel's content (but not its container).
-	 *
-	 * Class variables for this panel class are available in the `data` JS object;
-	 * export custom variables by overriding WP_Customize_Panel::json().
-	 *
-	 * @since 4.3.0
-	 * @access protected
-	 *
-	 * @see WP_Customize_Panel::print_template()
-	 */
-	protected function content_template() {
-		?>
-		<li class="panel-meta customize-info accordion-section <# if ( ! data.description ) { #> cannot-expand<# } #>">
-			<button type="button" class="customize-panel-back" tabindex="-1">
-				<span class="screen-reader-text"><?php _e( 'Back' ); ?></span>
-			</button>
-			<div class="accordion-section-title">
-				<span class="preview-notice">
-					<?php
-					/* Translators: %s is the site/panel title in the Customizer. */
-					printf( __( 'You are customizing %s' ), '<strong class="panel-title">{{ data.title }}</strong>' );
-					?>
-				</span>
-				<button type="button" class="customize-help-toggle dashicons dashicons-editor-help" aria-expanded="false">
-					<span class="screen-reader-text"><?php _e( 'Help' ); ?></span>
-				</button>
-				<button type="button" class="customize-screen-options-toggle" aria-expanded="false">
-					<span class="screen-reader-text"><?php _e( 'Menu Options' ); ?></span>
-				</button>
-			</div>
-			<# if ( data.description ) { #>
-			<div class="description customize-panel-description">{{{ data.description }}}</div>
-			<# } #>
-			<div id="screen-options-wrap">
-				<?php $this->render_screen_options(); ?>
-			</div>
-		</li>
-	<?php
-	}
-}
+/** WP_Customize_Nav_Menus_Panel class */
+require_once( ABSPATH . WPINC . '/customize/class-wp-customize-nav-menus-panel.php' );
diff --git a/wp-includes/customize/class-wp-customize-nav-menus-panel.php b/wp-includes/customize/class-wp-customize-nav-menus-panel.php
new file mode 100644
index 0000000000..e3be24b003
--- /dev/null
+++ b/wp-includes/customize/class-wp-customize-nav-menus-panel.php
@@ -0,0 +1,107 @@
+<?php
+/**
+ * Customize API: WP_Customize_Nav_Menus_Panel class
+ *
+ * @package WordPress
+ * @subpackage Customize
+ * @since 4.4.0
+ */
+
+/**
+ * Customize Nav Menus Panel Class
+ *
+ * Needed to add screen options.
+ *
+ * @since 4.3.0
+ *
+ * @see WP_Customize_Panel
+ */
+class WP_Customize_Nav_Menus_Panel extends WP_Customize_Panel {
+
+	/**
+	 * Control type.
+	 *
+	 * @since 4.3.0
+	 * @access public
+	 * @var string
+	 */
+	public $type = 'nav_menus';
+
+	/**
+	 * Render screen options for Menus.
+	 *
+	 * @since 4.3.0
+	 * @access public
+	 */
+	public function render_screen_options() {
+		// Essentially adds the screen options.
+		add_filter( 'manage_nav-menus_columns', array( $this, 'wp_nav_menu_manage_columns' ) );
+
+		// Display screen options.
+		$screen = WP_Screen::get( 'nav-menus.php' );
+		$screen->render_screen_options( array( 'wrap' => false ) );
+	}
+
+	/**
+	 * Returns the advanced options for the nav menus page.
+	 *
+	 * Link title attribute added as it's a relatively advanced concept for new users.
+	 *
+	 * @since 4.3.0
+	 * @access public
+	 *
+	 * @return array The advanced menu properties.
+	 */
+	public function wp_nav_menu_manage_columns() {
+		return array(
+			'_title'      => __( 'Show advanced menu properties' ),
+			'cb'          => '<input type="checkbox" />',
+			'link-target' => __( 'Link Target' ),
+			'attr-title'  => __( 'Title Attribute' ),
+			'css-classes' => __( 'CSS Classes' ),
+			'xfn'         => __( 'Link Relationship (XFN)' ),
+			'description' => __( 'Description' ),
+		);
+	}
+
+	/**
+	 * An Underscore (JS) template for this panel's content (but not its container).
+	 *
+	 * Class variables for this panel class are available in the `data` JS object;
+	 * export custom variables by overriding WP_Customize_Panel::json().
+	 *
+	 * @since 4.3.0
+	 * @access protected
+	 *
+	 * @see WP_Customize_Panel::print_template()
+	 */
+	protected function content_template() {
+		?>
+		<li class="panel-meta customize-info accordion-section <# if ( ! data.description ) { #> cannot-expand<# } #>">
+			<button type="button" class="customize-panel-back" tabindex="-1">
+				<span class="screen-reader-text"><?php _e( 'Back' ); ?></span>
+			</button>
+			<div class="accordion-section-title">
+				<span class="preview-notice">
+					<?php
+					/* Translators: %s is the site/panel title in the Customizer. */
+					printf( __( 'You are customizing %s' ), '<strong class="panel-title">{{ data.title }}</strong>' );
+					?>
+				</span>
+				<button type="button" class="customize-help-toggle dashicons dashicons-editor-help" aria-expanded="false">
+					<span class="screen-reader-text"><?php _e( 'Help' ); ?></span>
+				</button>
+				<button type="button" class="customize-screen-options-toggle" aria-expanded="false">
+					<span class="screen-reader-text"><?php _e( 'Menu Options' ); ?></span>
+				</button>
+			</div>
+			<# if ( data.description ) { #>
+			<div class="description customize-panel-description">{{{ data.description }}}</div>
+			<# } #>
+			<div id="screen-options-wrap">
+				<?php $this->render_screen_options(); ?>
+			</div>
+		</li>
+	<?php
+	}
+}