diff --git a/header.php b/header.php
index c0fff59..4e0db0f 100644
--- a/header.php
+++ b/header.php
@@ -68,6 +68,7 @@
 				<a class="header__nav-icon js-header-nav-toggle" href="#navigation"><?php _e( 'Toggle Menu', 'pressbooks-book' ); ?><span class="header__nav-icon__icon"></span></a>
 				<?php wp_nav_menu( [
 					'theme_location' => 'primary-menu',
+					'fallback_cb' => '\Aldine\Helpers\default_menu',
 					'container' => 'nav',
 					'container_class' => 'js-header-nav',
 					'container_id' => 'navigation',
diff --git a/inc/filters/namespace.php b/inc/filters/namespace.php
index 32e90be..86bead7 100644
--- a/inc/filters/namespace.php
+++ b/inc/filters/namespace.php
@@ -106,51 +106,7 @@ function add_blocks( $init_array ) {
 
 function adjust_menu( $items, $args ) {
 	if ( $args->theme_location === 'primary-menu' ) {
-		if ( ! is_front_page() ) {
-			$items = sprintf(
-				'<li><a href="%1$s">%2$s</a></li>',
-				'/',
-				__( 'Home', 'pressbooks-aldine' )
-			) . $items;
-		}
-		if ( get_option( 'pb_network_contact_form' ) ) {
-			$items .= sprintf(
-				'<li><a href="%1$s">%2$s</a></li>',
-				'#contact',
-				__( 'Contact', 'pressbooks-aldine' )
-			);
-		}
-		if ( ! is_user_logged_in() ) {
-			$items .= sprintf(
-				'<li><a href="%1$s">%2$s</a></li>',
-				wp_login_url( get_permalink() ),
-				__( 'Sign In', 'pressbooks-aldine' )
-			);
-			if ( in_array( get_site_option( 'registration' ), [ 'user', 'all' ], true ) ) {
-				$items .= sprintf(
-					'<li><a href="%1$s">%2$s</a></li>',
-					network_home_url( '/wp-signup.php' ),
-					__( 'Sign Up', 'pressbooks-aldine' )
-				);
-			}
-		} else {
-			if ( is_super_admin() || is_user_member_of_blog() ) {
-				$items .= sprintf(
-					'<li><a href="%1$s">%2$s</a></li>',
-					admin_url(),
-					__( 'Admin', 'pressbooks-aldine' )
-				);
-			}
-			$items .= sprintf(
-				'<li><a href="%1$s">%2$s</a></li>',
-				wp_logout_url( get_permalink() ),
-				__( 'Sign Out', 'pressbooks-aldine' )
-			);
-		}
-		/* @codingStandardsIgnoreStart $items .= sprintf(
-			'<li class="header__search js-search"><div class="header__search__form">%s</div></li>',
-			get_search_form( false )
-		); @codingStandardsIgnoreEnd */
+		return \Aldine\Helpers\get_default_menu( $items );
 	}
 
 	return $items;
diff --git a/inc/helpers/namespace.php b/inc/helpers/namespace.php
index 706e037..c4ef836 100644
--- a/inc/helpers/namespace.php
+++ b/inc/helpers/namespace.php
@@ -64,6 +64,75 @@ function get_catalog_licenses() {
 	return [];
 }
 
+/**
+ * Return the default (non-page) menu items.
+ *
+ * @param string $items
+ * @return string $items
+ */
+function get_default_menu( $items = '' ) {
+	if ( ! is_front_page() ) {
+		$items = sprintf(
+			'<li><a href="%1$s">%2$s</a></li>',
+			'/',
+			__( 'Home', 'pressbooks-aldine' )
+		) . $items;
+	}
+	if ( get_option( 'pb_network_contact_form' ) ) {
+		$items .= sprintf(
+			'<li><a href="%1$s">%2$s</a></li>',
+			'#contact',
+			__( 'Contact', 'pressbooks-aldine' )
+		);
+	}
+	if ( ! is_user_logged_in() ) {
+		$items .= sprintf(
+			'<li><a href="%1$s">%2$s</a></li>',
+			wp_login_url( get_permalink() ),
+			__( 'Sign In', 'pressbooks-aldine' )
+		);
+		if ( in_array( get_site_option( 'registration' ), [ 'user', 'all' ], true ) ) {
+			$items .= sprintf(
+				'<li><a href="%1$s">%2$s</a></li>',
+				network_home_url( '/wp-signup.php' ),
+				__( 'Sign Up', 'pressbooks-aldine' )
+			);
+		}
+	} else {
+		if ( is_super_admin() || is_user_member_of_blog() ) {
+			$items .= sprintf(
+				'<li><a href="%1$s">%2$s</a></li>',
+				admin_url(),
+				__( 'Admin', 'pressbooks-aldine' )
+			);
+		}
+		$items .= sprintf(
+			'<li><a href="%1$s">%2$s</a></li>',
+			wp_logout_url( get_permalink() ),
+			__( 'Sign Out', 'pressbooks-aldine' )
+		);
+	}
+	/* @codingStandardsIgnoreStart $items .= sprintf(
+		'<li class="header__search js-search"><div class="header__search__form">%s</div></li>',
+		get_search_form( false )
+	); @codingStandardsIgnoreEnd */
+
+	return $items;
+}
+
+/**
+ * Echo the default menu.
+ *
+ * @param string $items
+ * @return null
+ */
+function default_menu( $args = [], $items = '' ) {
+	printf(
+		"<{$args['container']} id='{$args['container_id']}' class='{$args['container_class']}'><ul id='{$args['menu_id']}' class='{$args['menu_class']}'>%s</ul></{$args['container']}>",
+		get_default_menu( $items )
+	);
+}
+
 /**
  *
  * Handler for contact form submissions.