diff --git a/changelog.txt b/changelog.txt
deleted file mode 100644
index 4d94867..0000000
--- a/changelog.txt
+++ /dev/null
@@ -1,39 +0,0 @@
-== Changelog ==
-
-= 1.0.7 =
-* 2022-09-11
-* Compatibility: WordPress 6.1
-* Minor refactoring
-
-= 1.0.6 =
-* 2022-05-06
-* Compatibility: WordPress 4.9 - WordPress 6.0
-* Compatibility: PHP 5.6.20 - PHP 8.1
-
-= 1.0.5 =
-* 2021-11-05
-* Compatibility: WordPress 4.9 - WordPress 5.9
-* Compatibility: PHP 5.6.20 - PHP 8.1
-
-= 1.0.4 =
-* 2021-06-23
-* Compatibility: WordPress 5.8
-
-= 1.0.3 =
-* 2021-02-14
-* Compatibility: WordPress 5.7
-
-= 1.0.2 =
-* 2020-11-30
-* Compatibility: WordPress 5.6
-* Compatibility: PHP 8.0
-
-= 1.0.1 =
-* 2020-07-22
-* Compatibility: WordPress 5.5
-
-= 1.0.0 =
-* Compatibility: WordPress 5.4
-
-= 0.1 =
-* First version.
diff --git a/noindex-seo.php b/noindex-seo.php
index 7051e00..805dd75 100644
--- a/noindex-seo.php
+++ b/noindex-seo.php
@@ -3,11 +3,11 @@
 Plugin Name: noindex SEO
 Plugin URI: https://wordpress.org/plugins/noindex-seo/
 Description: Allows to add a meta-tag for robots noindex in some parts of your WordPress site.
-Version: 1.0.7
-Requires at least: 4.9
-Tested: 6.1
-Requires PHP: 5.6.20
-Tested PHP: 8.1
+Version: 1.0.9
+Requires at least: 5.2
+Tested: 6.3
+Requires PHP: 7.0
+Tested PHP: 8.3
 Author: Javier Casares
 Author URI: https://www.javiercasares.com/
 License: EUPL 1.2
@@ -51,12 +51,12 @@ function noindex_seo_show()
   /*
     GLOBAL IMPORTANT PAGES
   */
-  if( $enter && $noindex_seo_values['front_page'] && is_front_page() )
+  if( $enter && $noindex_seo_values['front_page'] && function_exists( 'is_front_page' ) && is_front_page() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['home'] && is_home() )
+  if( $enter && $noindex_seo_values['home'] && function_exists( 'is_home' ) && is_home() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -65,22 +65,22 @@ function noindex_seo_show()
   /*
     PAGES / POSTS
   */
-  if( $enter && $noindex_seo_values['page'] && is_page() )
+  if( $enter && $noindex_seo_values['page'] && function_exists( 'is_page' ) && is_page() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['privacy_policy'] && is_privacy_policy() )
+  if( $enter && $noindex_seo_values['privacy_policy'] && function_exists( 'is_privacy_policy' ) && is_privacy_policy() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['single'] && is_single() )
+  if( $enter && $noindex_seo_values['single'] && function_exists( 'is_single' ) && is_single() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['singular'] && is_singular() )
+  if( $enter && $noindex_seo_values['singular'] && function_exists( 'is_singular' ) && is_singular() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -89,12 +89,12 @@ function noindex_seo_show()
   /*
     CATEGORIES / TAGS
   */
-  if( $enter && $noindex_seo_values['category'] && is_category() )
+  if( $enter && $noindex_seo_values['category'] && function_exists( 'is_category' ) && is_category() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['tag'] && is_tag() )
+  if( $enter && $noindex_seo_values['tag'] && function_exists( 'is_tag' ) && is_tag() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -103,27 +103,27 @@ function noindex_seo_show()
   /*
     DATES
   */
-  if( $enter && $noindex_seo_values['date'] && is_date() )
+  if( $enter && $noindex_seo_values['date'] && function_exists( 'is_date' ) && is_date() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['day'] && is_day() )
+  if( $enter && $noindex_seo_values['day'] && function_exists( 'is_day' ) && is_day() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['month'] && is_month() )
+  if( $enter && $noindex_seo_values['month'] && function_exists( 'is_month' ) && is_month() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['time'] && is_time() )
+  if( $enter && $noindex_seo_values['time'] && function_exists( 'is_time' ) && is_time() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['year'] && is_year() )
+  if( $enter && $noindex_seo_values['year'] && function_exists( 'is_year' ) && is_year() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -132,17 +132,17 @@ function noindex_seo_show()
   /*
     ARCHIVE
   */
-  if( $enter && $noindex_seo_values['archive'] && is_archive() )
+  if( $enter && $noindex_seo_values['archive'] && function_exists( 'is_archive' ) && is_archive() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['author'] && is_author() )
+  if( $enter && $noindex_seo_values['author'] && function_exists( 'is_author' ) && is_author() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['post_type_archive'] && is_post_type_archive() )
+  if( $enter && $noindex_seo_values['post_type_archive'] && function_exists( 'is_post_type_archive' ) && is_post_type_archive() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -151,7 +151,7 @@ function noindex_seo_show()
   /*
     PAGINATION
   */
-  if( $enter && $noindex_seo_values['paged'] && is_paged() )
+  if( $enter && $noindex_seo_values['paged'] && function_exists( 'is_paged' ) && is_paged() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -160,7 +160,7 @@ function noindex_seo_show()
   /*
     SEARCH
   */
-  if( $enter && $noindex_seo_values['search'] && is_search() )
+  if( $enter && $noindex_seo_values['search'] && function_exists( 'is_search' ) && is_search() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -169,7 +169,7 @@ function noindex_seo_show()
   /*
     ATTACHMENT
   */
-  if( $enter && $noindex_seo_values['attachment'] && is_attachment() )
+  if( $enter && $noindex_seo_values['attachment'] && function_exists( 'is_attachment' ) && is_attachment() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -178,12 +178,12 @@ function noindex_seo_show()
   /*
     PREVIEW
   */
-  if( $enter && $noindex_seo_values['customize_preview'] && is_customize_preview() )
+  if( $enter && $noindex_seo_values['customize_preview'] && function_exists( 'is_customize_preview' ) && is_customize_preview() )
   {
     noindex_seo_metarobots();
     $enter = false;
   }
-  if( $enter && $noindex_seo_values['preview'] && is_preview() )
+  if( $enter && $noindex_seo_values['preview'] && function_exists( 'is_preview' ) && is_preview() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -192,7 +192,7 @@ function noindex_seo_show()
   /*
     ERROR
   */
-  if( $enter && $noindex_seo_values['error'] && is_404() )
+  if( $enter && $noindex_seo_values['error'] && function_exists( 'is_404' ) && is_404() )
   {
     noindex_seo_metarobots();
     $enter = false;
@@ -202,14 +202,14 @@ function noindex_seo_show()
     FEED
   */
   /*
-  if( $enter && $noindex_seo_values['comment_feed'] && is_comment_feed() )
+  if( $enter && $noindex_seo_values['comment_feed'] && function_exists( 'is_comment_feed' ) && is_comment_feed() )
   {
     add_action( 'wp_headers', 'noindex_seo_xrobots' );
     $enter = false;
   }
   */
   /*
-  if( $enter && $noindex_seo_values['feed'] && is_feed() )
+  if( $enter && $noindex_seo_values['feed'] && function_exists( 'is_feed' ) && is_feed() )
   {
     add_action( 'wp_headers', 'noindex_seo_xrobots' );
     $enter = false;
@@ -220,7 +220,7 @@ function noindex_seo_show()
     ROBOTS
   */
   /*
-  if( $enter && $noindex_seo_values['robots'] && is_robots() )
+  if( $enter && $noindex_seo_values['robots'] && function_exists( 'is_robots' ) && is_robots() )
   {
     add_action( 'do_robotstxt', 'noindex_seo_xrobots' );
     $enter = false;
diff --git a/readme.txt b/readme.txt
index 5a4f1fa..42fe211 100644
--- a/readme.txt
+++ b/readme.txt
@@ -1,34 +1,39 @@
 === noindex SEO ===
 Contributors: javiercasares
 Tags: seo, noindex
-Requires at least: 4.9
-Tested: 6.1
-Requires PHP: 5.6.20
-Tested PHP: 8.1
-Stable tag: 1.0.7
+Requires at least: 5.2
+Tested: 6.3
+Requires PHP: 7.0
+Tested PHP: 8.3
+Stable tag: 1.0.9
 License: EUPL 1.2
 License URI: https://eupl.eu/1.2/en/
 
 Allows to add a meta-tag for robots noindex in some parts of your WordPress site.
 
 == Description ==
+
 Allows to add a meta-tag for robots noindex in some parts of your WordPress site.
 
 Main pages
+
 * Front Page: Block the indexing of the site's front page.
 * Home: Block the indexing of the site's home page.
 
 Pages and Posts
+
 * Page: Block the indexing of the site's pages.
 * Privacy Policy: Block the indexing of the site's privacy policy page.
 * Single: Block the indexing of a post on the site.
 * Singular: Block the indexing of a post or a page of the site.
 
 Taxonomies
+
 * Category: Block the indexing of the site categories. The lists where the posts appear.
 * Tag: Block the indexing of the site's tags. The lists where the posts appear.
 
 Dates
+
 * Date: Block the indexing when any date-based archive page (i.e. a monthly, yearly, daily or time-based archive) of the site. The lists where the posts appear.
 * Day: Block the indexing when a daily archive of the site. The lists where the posts appear.
 * Month: Block the indexing when a monthly archive of the site. The lists where the posts appear.
@@ -36,48 +41,68 @@ Dates
 * Year: Block the indexing when a yearly archive of the site. The lists where the posts appear.
 
 Archives
+
 * Archive: Block the indexing of any type of Archive page. Category, Tag, Author and Date based pages are all types of Archives. The lists where the posts appear.
 * Author: Block the indexing of the author's page, where the author's publications appear.
 * Post Type Archive: Block the indexing of any post type page.
 
 Pagination
+
 * Pagination: Block the indexing of the pagination, i.e. all pages other than the main page of an archive.
 
 Search
+
 * Search: Block the indexing of the internal search result pages.
 
 Attachments
+
 * Attachment: Block the indexing of an attachment document to a post or page. An attachment is an image or other file uploaded through the post editor's upload utility. Attachments can be displayed on their own "page" or template. This will not cause the indexing of the image or file to be blocked.
 
 Previews
+
 * Customize Preview: Block the indexing when a content is being displayed in customize mode.
 * Preview: Block the indexing when a single post is being displayed in draft mode.
 
 Error Page
+
 * Error 404: This will cause an error page to be blocked from being indexed. As it is an error page, it should not be indexed per se, but just in case.
 
 Important note: if you have any doubt about any of the following items it is best not to activate the option as you could lose results in the search engines.
 
 == Installation ==
+
 1. Use the Add New Plugin in the WordPress Admin area
 2. Activate the plugin through the Plugins menu in WordPress
 3. You can find the settings and documentation under Settings -> noindex
 
 == Changelog ==
 
+= 1.0.9 =
+* 2023-07-28
+* Improved functions checking.
+* Compatibility: WordPress 5.2 - WordPress 6.3.
+* Compatibility: PHP 7.0 - PHP 8.3.
+
+= 1.0.8 =
+* 2023-02-20
+* Compatibility: WordPress 5.2 - WordPress 6.2
+* Compatibility: PHP 7.2 - PHP 8.1
+
 = 1.0.7 =
 * 2022-09-11
-* Compatibility: WordPress 6.1
+* Compatibility: WordPress 4.9 - WordPress 6.1
+* Compatibility: PHP 5.6.20 - PHP 8.1
 * Minor refactoring
 
 = 1.0.6 =
 * 2022-05-06
-* Compatibility: WordPress 6.0
+* Compatibility: WordPress 4.9 - WordPress 6.0
+* Compatibility: PHP 5.6.20 - PHP 8.1
 
 = 1.0.5 =
 * 2021-11-05
-* Update the Plugin URI for WordPress 5.8
-* Compatibility: PHP 8.1
+* Compatibility: WordPress 4.9 - WordPress 5.9
+* Compatibility: PHP 5.6.20 - PHP 8.1
 
 = 1.0.4 =
 * 2021-06-23