diff --git a/assets/src/components/reader-themes-context-provider/index.js b/assets/src/components/reader-themes-context-provider/index.js
index 8b8e8df5865..38cfb5c48d7 100644
--- a/assets/src/components/reader-themes-context-provider/index.js
+++ b/assets/src/components/reader-themes-context-provider/index.js
@@ -9,7 +9,7 @@ import { __ } from '@wordpress/i18n';
  * External dependencies
  */
 import PropTypes from 'prop-types';
-import { READER_THEME_AVAILABLE, LEGACY_THEME_SLUG } from 'amp-settings';
+import { USING_FALLBACK_READER_THEME, LEGACY_THEME_SLUG } from 'amp-settings';
 
 /**
  * Internal dependencies
@@ -92,7 +92,7 @@ export function ReaderThemesContextProvider( { wpAjaxUrl, children, currentTheme
 		if (
 			selectedTheme.availability === 'non-installable' ||
 			originalSelectedTheme.availability === 'active' ||
-			! READER_THEME_AVAILABLE
+			USING_FALLBACK_READER_THEME
 		) {
 			updateOptions( { reader_theme: LEGACY_THEME_SLUG } );
 			setThemeWasOverridden( true );
diff --git a/includes/options/class-amp-options-manager.php b/includes/options/class-amp-options-manager.php
index f7295e25e1b..0f22f3c697a 100644
--- a/includes/options/class-amp-options-manager.php
+++ b/includes/options/class-amp-options-manager.php
@@ -520,7 +520,9 @@ public static function reader_theme_fallback_notice() {
 			return;
 		}
 
-		if ( amp_is_legacy() && ReaderThemes::DEFAULT_READER_THEME !== self::get_option( Option::READER_THEME ) && current_user_can( 'manage_options' ) ) {
+		$reader_themes = new ReaderThemes();
+
+		if ( $reader_themes->using_fallback_theme() ) {
 			$selected_theme = self::get_option( Option::READER_THEME );
 			$error_message  = sprintf(
 				/* translators: 1: slug of the Reader theme, 2: the URL for the reader theme selection UI */
diff --git a/src/Admin/OnboardingWizardSubmenuPage.php b/src/Admin/OnboardingWizardSubmenuPage.php
index 96357d46445..0fe6f37e60f 100644
--- a/src/Admin/OnboardingWizardSubmenuPage.php
+++ b/src/Admin/OnboardingWizardSubmenuPage.php
@@ -213,7 +213,6 @@ public function enqueue_assets( $hook_suffix ) {
 		wp_styles()->add_data( self::ASSET_HANDLE, 'rtl', 'replace' );
 
 		$theme           = wp_get_theme();
-		$reader_theme    = AMP_Options_Manager::get_option( Option::READER_THEME );
 		$is_reader_theme = $this->reader_themes->theme_data_exists( get_stylesheet() );
 
 		$exit_link = menu_page_url( AMP_Options_Manager::OPTION_NAME, false );
@@ -240,7 +239,7 @@ public function enqueue_assets( $hook_suffix ) {
 				'screenshot'      => $theme->get_screenshot() ?: null,
 				'url'             => $theme->get( 'ThemeURI' ),
 			],
-			'READER_THEME_AVAILABLE'             => $this->reader_themes->theme_data_exists( $reader_theme ),
+			'USING_FALLBACK_READER_THEME'        => $this->reader_themes->using_fallback_theme(),
 			'FINISH_LINK'                        => $exit_link,
 			'OPTIONS_REST_PATH'                  => '/amp/v1/options',
 			'READER_THEMES_REST_PATH'            => '/amp/v1/reader-themes',
diff --git a/src/Admin/OptionsMenu.php b/src/Admin/OptionsMenu.php
index 7ee801b6f09..e534a199df8 100644
--- a/src/Admin/OptionsMenu.php
+++ b/src/Admin/OptionsMenu.php
@@ -195,29 +195,28 @@ public function enqueue_assets( $hook_suffix ) {
 		wp_styles()->add_data( self::ASSET_HANDLE, 'rtl', 'replace' );
 
 		$theme           = wp_get_theme();
-		$reader_theme    = AMP_Options_Manager::get_option( Option::READER_THEME );
 		$is_reader_theme = $this->reader_themes->theme_data_exists( get_stylesheet() );
 
 		$js_data = [
-			'CURRENT_THEME'              => [
+			'CURRENT_THEME'               => [
 				'name'            => $theme->get( 'Name' ),
 				'description'     => $theme->get( 'Description' ),
 				'is_reader_theme' => $is_reader_theme,
 				'screenshot'      => $theme->get_screenshot() ?: null,
 				'url'             => $theme->get( 'ThemeURI' ),
 			],
-			'OPTIONS_REST_PATH'          => '/amp/v1/options',
-			'READER_THEMES_REST_PATH'    => '/amp/v1/reader-themes',
-			'IS_CORE_THEME'              => in_array(
+			'OPTIONS_REST_PATH'           => '/amp/v1/options',
+			'READER_THEMES_REST_PATH'     => '/amp/v1/reader-themes',
+			'IS_CORE_THEME'               => in_array(
 				get_stylesheet(),
 				AMP_Core_Theme_Sanitizer::get_supported_themes(),
 				true
 			),
-			'LEGACY_THEME_SLUG'          => ReaderThemes::DEFAULT_READER_THEME,
-			'READER_THEME_AVAILABLE'     => $this->reader_themes->theme_data_exists( $reader_theme ),
-			'THEME_SUPPORT_ARGS'         => AMP_Theme_Support::get_theme_support_args(),
-			'THEME_SUPPORTS_READER_MODE' => AMP_Theme_Support::supports_reader_mode(),
-			'UPDATES_NONCE'              => wp_create_nonce( 'updates' ),
+			'LEGACY_THEME_SLUG'           => ReaderThemes::DEFAULT_READER_THEME,
+			'USING_FALLBACK_READER_THEME' => $this->reader_themes->using_fallback_theme(),
+			'THEME_SUPPORT_ARGS'          => AMP_Theme_Support::get_theme_support_args(),
+			'THEME_SUPPORTS_READER_MODE'  => AMP_Theme_Support::supports_reader_mode(),
+			'UPDATES_NONCE'               => wp_create_nonce( 'updates' ),
 		];
 
 		wp_add_inline_script(
diff --git a/src/Admin/ReaderThemes.php b/src/Admin/ReaderThemes.php
index 3ba440f6ac6..96b9cdb1afe 100644
--- a/src/Admin/ReaderThemes.php
+++ b/src/Admin/ReaderThemes.php
@@ -346,6 +346,12 @@ public function theme_data_exists( $theme_slug ) {
 		return in_array( $theme_slug, wp_list_pluck( $this->get_themes(), 'slug' ), true );
 	}
 
+	public function using_fallback_theme() {
+		return amp_is_legacy()
+			&& self::DEFAULT_READER_THEME !== AMP_Options_Manager::get_option( Option::READER_THEME )
+			&& current_user_can( 'manage_options' );
+	}
+
 	/**
 	 * Provides details for the legacy theme included with the plugin.
 	 *