diff --git a/.travis.yml b/.travis.yml
index 61ebd09..193cb2d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -25,7 +25,7 @@ matrix:
     - php: 7.0
       env: WP_VERSION=latest
     - php: 5.6
-      env: WP_VERSION=4.3
+      env: WP_VERSION=4.7
     - php: 5.6
       env: WP_TRAVISCI=phpcs
 before_script:
@@ -40,7 +40,7 @@ before_script:
   - |
     if [[ ! -z "$WP_VERSION" ]] ; then
       bash bin/install-wp-tests.sh wordpress_test root '' localhost $WP_VERSION
-      composer global require "phpunit/phpunit=4.8.*|5.7.*"
+      composer global require "phpunit/phpunit=5.7.*|6.*.*|7.*.*"
     fi
   - |
     if [[ "$WP_TRAVISCI" == "phpcs" ]] ; then
diff --git a/.wp-env.json b/.wp-env.json
new file mode 100644
index 0000000..4dce042
--- /dev/null
+++ b/.wp-env.json
@@ -0,0 +1,5 @@
+{
+    "plugins": [ "." ],
+    "port": 50080,
+    "testsPort": 50081
+}
diff --git a/CPTP/Module/Admin.php b/CPTP/Module/Admin.php
index 51442e8..0b53fd2 100644
--- a/CPTP/Module/Admin.php
+++ b/CPTP/Module/Admin.php
@@ -76,7 +76,7 @@ public function settings_api_init() {
 			)
 		);
 
-		register_setting( 'permalink', 'no_taxonomy_structure' );
+		register_setting( 'permalink', 'add_post_type_for_tax' );
 	}
 
 	/**
@@ -175,7 +175,6 @@ public function add_post_type_for_tax_callback_function() {
 		esc_html_e( 'There are cases when the template to be loaded is changed.', 'custom-post-type-permalinks' );
 	}
 
-
 	/**
 	 * Enqueue css and js
 	 *
diff --git a/CPTP/Module/Option.php b/CPTP/Module/Option.php
index 57b3e78..ac64e2b 100644
--- a/CPTP/Module/Option.php
+++ b/CPTP/Module/Option.php
@@ -72,8 +72,8 @@ public function save_options() {
 		$no_taxonomy_structure = ! filter_input( INPUT_POST, 'no_taxonomy_structure' );
 		$add_post_type_for_tax = filter_input( INPUT_POST, 'add_post_type_for_tax' );
 
-		update_option( 'no_taxonomy_structure', $no_taxonomy_structure );
-		update_option( 'add_post_type_for_tax', $add_post_type_for_tax );
+		update_option( 'no_taxonomy_structure', ! ! $no_taxonomy_structure );
+		update_option( 'add_post_type_for_tax', ! ! $add_post_type_for_tax );
 		update_option( 'cptp_permalink_checked', CPTP_VERSION );
 	}
 
diff --git a/CPTP/Module/Permalink.php b/CPTP/Module/Permalink.php
index a6c54cb..207f263 100644
--- a/CPTP/Module/Permalink.php
+++ b/CPTP/Module/Permalink.php
@@ -37,6 +37,13 @@ public function add_hook() {
 			apply_filters( 'cptp_attachment_link_priority', 20 ),
 			2
 		);
+
+		add_filter(
+			'wpml_st_post_type_link_filter_original_slug',
+			array( $this, 'replace_post_slug_with_placeholder' ),
+			10,
+			3
+		);
 	}
 
 
@@ -90,7 +97,7 @@ public function post_type_link( $post_link, $post, $leavename ) {
 		$permalink = $wp_rewrite->get_extra_permastruct( $post_type );
 
 		$permalink = str_replace( '%post_id%', $post->ID, $permalink );
-		$permalink = str_replace( '%' . $post_type . '_slug%', $pt_object->rewrite['slug'], $permalink );
+		$permalink = str_replace( CPTP_Module_Rewrite::get_slug_placeholder( $post_type ), $pt_object->rewrite['slug'], $permalink );
 
 		// has parent.
 		$parentsDirs = '';
@@ -388,4 +395,18 @@ public function term_link( $termlink, $term, $taxonomy ) {
 
 		return $termlink;
 	}
+
+	/**
+	 * This filter is needed for WPML's compatibility. It will return
+	 * the slug placeholder instead of the original CPT slug.
+	 *
+	 * @param string  $original_slug The original CPT slug.
+	 * @param string  $post_link     The post link.
+	 * @param WP_Post $post          The post.
+	 *
+	 * @return string
+	 */
+	public function replace_post_slug_with_placeholder( $original_slug, $post_link, $post ) {
+		return CPTP_Module_Rewrite::get_slug_placeholder( $post->post_type );
+	}
 }
diff --git a/CPTP/Module/Rewrite.php b/CPTP/Module/Rewrite.php
index 826ca50..1ac3593 100644
--- a/CPTP/Module/Rewrite.php
+++ b/CPTP/Module/Rewrite.php
@@ -59,10 +59,11 @@ public function register_post_type_rules( $post_type, $args ) {
 			$permalink = CPTP_DEFAULT_PERMALINK;
 		}
 
-		$permalink = '%' . $post_type . '_slug%' . $permalink;
-		$permalink = str_replace( '%postname%', '%' . $post_type . '%', $permalink );
+		$slug_placeholder = self::get_slug_placeholder( $post_type );
+		$permalink        = $slug_placeholder . $permalink;
+		$permalink        = str_replace( '%postname%', '%' . $post_type . '%', $permalink );
 
-		add_rewrite_tag( '%' . $post_type . '_slug%', '(' . $args->rewrite['slug'] . ')', 'post_type=' . $post_type . '&slug=' );
+		add_rewrite_tag( $slug_placeholder, '(' . $args->rewrite['slug'] . ')', 'post_type=' . $post_type . '&slug=' );
 
 		$taxonomies = CPTP_Util::get_taxonomies( true );
 		foreach ( $taxonomies as $taxonomy => $objects ) :
@@ -280,4 +281,15 @@ public function parse_request( $obj ) {
 			}
 		}
 	}
+
+	/**
+	 * Returns the slug placeholder user in the permalink structure.
+	 *
+	 * @param string $post_type The post type.
+	 *
+	 * @return string
+	 */
+	public static function get_slug_placeholder( $post_type ) {
+		return '%' . $post_type . '_slug%';
+	}
 }
diff --git a/codesniffer.ruleset.xml b/codesniffer.ruleset.xml
index 7c08d42..98d4608 100644
--- a/codesniffer.ruleset.xml
+++ b/codesniffer.ruleset.xml
@@ -22,7 +22,7 @@
     <config name="testVersion" value="5.3-"/>
     <!-- https://github.com/PHPCompatibility/PHPCompatibilityWP -->
     <rule ref="PHPCompatibilityWP"/>
-    <config name="minimum_supported_wp_version" value="4.3"/>
+    <config name="minimum_supported_wp_version" value="4.7"/>
     <rule ref="WordPress-Core">
         <exclude name="WordPress.Files.FileName" />
         <exclude name="WordPress.NamingConventions.ValidVariableName.VariableNotSnakeCase" />
diff --git a/phpunit.xml b/phpunit.xml
index b019054..a224a8c 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -7,7 +7,7 @@
 	convertWarningsToExceptions="true"
 	>
 	<testsuites>
-		<testsuite>
+		<testsuite name="custom-post-type-permalinks">
 			<directory prefix="test-" suffix=".php">./tests/</directory>
 		</testsuite>
 	</testsuites>
diff --git a/readme.txt b/readme.txt
index 50bf9bf..39a9241 100644
--- a/readme.txt
+++ b/readme.txt
@@ -2,9 +2,9 @@
 Contributors:      Toro_Unit,inc2734,ixkaito,keita_kobayashi
 Donate link:       https://www.paypal.me/torounit
 Tags:              permalink,permalinks,custom post type,custom taxonomy,cms
-Requires at least: 4.3
+Requires at least: 4.7
 Tested up to:      5.4
-Requires PHP:      5.3
+Requires PHP:      5.6
 Stable tag: 3.3.5
 License: GPLv2 or Later
 
diff --git a/tests/test-cptp-module-permalink.php b/tests/test-cptp-module-permalink.php
index 602159c..1cf8d43 100644
--- a/tests/test-cptp-module-permalink.php
+++ b/tests/test-cptp-module-permalink.php
@@ -14,7 +14,6 @@ public function setUp() {
 		add_option( 'category_base', rand_str( 12 ) );
 		delete_option( 'tag_base' );
 		add_option( 'tag_base', rand_str( 12 ) );
-
 		$wp_rewrite->init();
 		$wp_rewrite->set_permalink_structure( '/%year%/%monthnum%/%day%/%postname%/' );
 		delete_option( 'no_taxonomy_structure' );
@@ -412,6 +411,28 @@ public function test_to_disable_post_type( $structure ) {
 		$this->assertTrue( is_attachment() );
 	}
 
+	/**
+	 * @test
+	 * @group permalink
+	 * @group wpml
+	 */
+	public function test_wpml_st_post_type_link_filter_original_slug() {
+		register_post_type( $this->post_type, array(
+			'public'     => true,
+		) );
+
+		$user_id = $this->factory->user->create();
+		$post = $this->factory->post->create_and_get( array(
+			'post_type'   => $this->post_type,
+			'post_author' => $user_id,
+		) );
+
+		$actual = apply_filters( 'wpml_st_post_type_link_filter_original_slug', 'ignored', 'ignored', $post );
 
+		$this->assertEquals(
+			CPTP_Module_Rewrite::get_slug_placeholder( $post->post_type ),
+			$actual
+		);
+	}
 }