diff --git a/CoinsPlugin.inc.php b/CoinsPlugin.inc.php
deleted file mode 100644
index 6adcff6..0000000
--- a/CoinsPlugin.inc.php
+++ /dev/null
@@ -1,133 +0,0 @@
-<?php
-
-/**
- * @file CoinsPlugin.inc.php
- *
- * Copyright (c) 2013-2021 Simon Fraser University
- * Copyright (c) 2003-2021 John Willinsky
- * Distributed under the GNU GPL v3. For full terms see the file LICENSE.
- *
- * @class CoinsPlugin
- * @brief COinS plugin class
- */
-
-import('lib.pkp.classes.plugins.GenericPlugin');
-
-class CoinsPlugin extends GenericPlugin {
-	/**
-	 * Called as a plugin is registered to the registry
-	 * @param $category String Name of category plugin was registered to
-	 * @return boolean True iff plugin initialized successfully; if false,
-	 * 	the plugin will not be registered.
-	 */
-	function register($category, $path, $mainContextId = null) {
-		$success = parent::register($category, $path, $mainContextId);
-		if (!Config::getVar('general', 'installed') || defined('RUNNING_UPGRADE')) return true;
-		if ($success && $this->getEnabled()) {
-			HookRegistry::register('Templates::Common::Footer::PageFooter', array($this, 'insertFooter'));
-		}
-		return $success;
-	}
-
-	/**
-	 * Get the display name of this plugin
-	 * @return string
-	 */
-	function getDisplayName() {
-		return __('plugins.generic.coins.displayName');
-	}
-
-	/**
-	 * Get the description of this plugin
-	 * @return string
-	 */
-	function getDescription() {
-		return __('plugins.generic.coins.description');
-	}
-
-	/**
-	 * Insert COinS tag.
-	 * @param $hookName string
-	 * @param $params array
-	 * @return boolean
-	 */
-	function insertFooter($hookName, $params) {
-		if ($this->getEnabled()) {
-			$request = Application::get()->getRequest();
-
-			// Ensure that the callback is being called from a page COinS should be embedded in.
-			if (!in_array($request->getRequestedPage() . '/' . $request->getRequestedOp(), array(
-				'article/view',
-			))) return false;
-
-			$smarty =& $params[1];
-			$output =& $params[2];
-			$templateMgr =& TemplateManager::getManager($request);
-
-			$article = $templateMgr->get_template_vars('article');
-			$journal = $templateMgr->get_template_vars('currentJournal');
-			$issue = $templateMgr->get_template_vars('issue');
-			$publication = $article->getCurrentPublication();
-
-			$vars = array(
-				array('ctx_ver', 'Z39.88-2004'),
-				array('rft_id', $request->url(null, 'article', 'view', $article->getId())),
-				array('rft_val_fmt', 'info:ofi/fmt:kev:mtx:journal'),
-				array('rft.language', $article->getLocale()),
-				array('rft.genre', 'article'),
-				array('rft.title', $journal->getLocalizedName()),
-				array('rft.jtitle', $journal->getLocalizedName()),
-				array('rft.atitle', $article->getFullTitle($article->getLocale())),
-				array('rft.artnum', $article->getBestArticleId()),
-				array('rft.stitle', $journal->getLocalizedSetting('abbreviation')),
-				array('rft.volume', $issue->getVolume()),
-				array('rft.issue', $issue->getNumber()),
-			);
-
-			$authors = $publication->getData('authors');
-			if ($firstAuthor = array_shift($authors)) {
-				$vars = array_merge($vars, array(
-					array('rft.aulast', $firstAuthor->getFamilyName($article->getLocale())),
-					array('rft.aufirst', $firstAuthor->getGivenName($article->getLocale())),
-				));
-			}
-
-			$datePublished = $article->getDatePublished();
-			if (!$datePublished) {
-				$datePublished = $issue->getDatePublished();
-			}
-
-			if ($datePublished) {
-				$vars[] = array('rft.date', date('Y-m-d', strtotime($datePublished)));
-			}
-
-			foreach ($authors as $author) {
-				$vars[] = array('rft.au', $author->getFullName());
-			}
-
-			if ($doi = $article->getStoredPubId('doi')) {
-				$vars[] = array('rft_id', 'info:doi/' . $doi);
-			}
-			if ($article->getPages()) {
-				$vars[] = array('rft.pages', $article->getPages());
-			}
-			if ($journal->getSetting('printIssn')) {
-				$vars[] = array('rft.issn', $journal->getSetting('printIssn'));
-			}
-			if ($journal->getSetting('onlineIssn')) {
-				$vars[] = array('rft.eissn', $journal->getSetting('onlineIssn'));
-			}
-
-			$title = '';
-			foreach ($vars as $entries) {
-				list($name, $value) = $entries;
-				$title .= $name . '=' . urlencode($value) . '&';
-			}
-			$title = htmlentities(substr($title, 0, -1));
-
-			$output .= "<span class=\"Z3988\" title=\"$title\"></span>\n";
-		}
-		return false;
-	}
-}
-
diff --git a/CoinsPlugin.php b/CoinsPlugin.php
new file mode 100644
index 0000000..f943efb
--- /dev/null
+++ b/CoinsPlugin.php
@@ -0,0 +1,137 @@
+<?php
+
+/**
+ * @file CoinsPlugin.php
+ *
+ * Copyright (c) 2013-2023 Simon Fraser University
+ * Copyright (c) 2003-2023 John Willinsky
+ * Distributed under the GNU GPL v3. For full terms see the file LICENSE.
+ *
+ * @class CoinsPlugin
+ * @brief COinS plugin class
+ */
+
+namespace APP\plugins\generic\coins;
+
+use PKP\plugins\GenericPlugin;
+use PKP\plugins\Hook;
+use PKP\config\Config;
+use APP\core\Application;
+use APP\template\TemplateManager;
+
+class CoinsPlugin extends GenericPlugin {
+    /**
+     * Called as a plugin is registered to the registry
+     * @param $category String Name of category plugin was registered to
+     * @return boolean True iff plugin initialized successfully; if false,
+     *     the plugin will not be registered.
+     */
+    function register($category, $path, $mainContextId = null) {
+        $success = parent::register($category, $path, $mainContextId);
+        if (!Config::getVar('general', 'installed') || defined('RUNNING_UPGRADE')) return true;
+        if ($success && $this->getEnabled()) {
+            Hook::add('Templates::Common::Footer::PageFooter', [$this, 'insertFooter']);
+        }
+        return $success;
+    }
+
+    /**
+     * Get the display name of this plugin
+     * @return string
+     */
+    function getDisplayName() {
+        return __('plugins.generic.coins.displayName');
+    }
+
+    /**
+     * Get the description of this plugin
+     * @return string
+     */
+    function getDescription() {
+        return __('plugins.generic.coins.description');
+    }
+
+    /**
+     * Insert COinS tag.
+     */
+    function insertFooter(string $hookName, array $params) : bool
+    {
+        if (!$this->getEnabled()) return false;
+        $request = Application::get()->getRequest();
+
+        // Ensure that the callback is being called from a page COinS should be embedded in.
+        if (!in_array($request->getRequestedPage() . '/' . $request->getRequestedOp(), [
+            'article/view',
+        ])) return false;
+
+        $smarty =& $params[1];
+        $output =& $params[2];
+        $templateMgr = TemplateManager::getManager($request);
+
+        $article = $templateMgr->getTemplateVars('article');
+        $journal = $templateMgr->getTemplateVars('currentJournal');
+        $issue = $templateMgr->getTemplateVars('issue');
+        $publication = $article->getCurrentPublication();
+
+        $vars = [
+            ['ctx_ver', 'Z39.88-2004'],
+            ['rft_id', $request->url(null, 'article', 'view', $article->getId())],
+            ['rft_val_fmt', 'info:ofi/fmt:kev:mtx:journal'],
+            ['rft.language', $article->getLocale()],
+            ['rft.genre', 'article'],
+            ['rft.title', $journal->getLocalizedName()],
+            ['rft.jtitle', $journal->getLocalizedName()],
+            ['rft.atitle', $article->getFullTitle($article->getLocale())],
+            ['rft.artnum', $article->getBestArticleId()],
+            ['rft.stitle', $journal->getLocalizedSetting('abbreviation')],
+            ['rft.volume', $issue->getVolume()],
+            ['rft.issue', $issue->getNumber()],
+        ];
+
+        $authors = $publication->getData('authors');
+        if ($firstAuthor = $authors->first()) {
+            $vars = array_merge($vars, [
+                ['rft.aulast', $firstAuthor->getFamilyName($article->getLocale())],
+                ['rft.aufirst', $firstAuthor->getGivenName($article->getLocale())],
+            ]);
+        }
+
+        $datePublished = $article->getDatePublished();
+        if (!$datePublished) {
+            $datePublished = $issue->getDatePublished();
+        }
+
+        if ($datePublished) {
+            $vars[] = ['rft.date', date('Y-m-d', strtotime($datePublished))];
+        }
+
+        foreach ($authors as $author) {
+            $vars[] = ['rft.au', $author->getFullName()];
+        }
+
+        if ($doi = $article->getStoredPubId('doi')) {
+            $vars[] = ['rft_id', 'info:doi/' . $doi];
+        }
+        if ($article->getPages()) {
+            $vars[] = ['rft.pages', $article->getPages()];
+        }
+        if ($journal->getSetting('printIssn')) {
+            $vars[] = ['rft.issn', $journal->getSetting('printIssn')];
+        }
+        if ($journal->getSetting('onlineIssn')) {
+            $vars[] = ['rft.eissn', $journal->getSetting('onlineIssn')];
+        }
+
+        $title = '';
+        foreach ($vars as $entries) {
+            list($name, $value) = $entries;
+            $title .= $name . '=' . urlencode($value) . '&';
+        }
+        $title = htmlentities(substr($title, 0, -1));
+
+	$output .= "<span class=\"Z3988\" title=\"$title\"></span>\n";
+
+	return false;
+    }
+}
+
diff --git a/index.php b/index.php
deleted file mode 100644
index 06cb604..0000000
--- a/index.php
+++ /dev/null
@@ -1,15 +0,0 @@
-<?php
-
-/**
- * @file index.php
- *
- * Copyright (c) 2013-2021 Simon Fraser University
- * Copyright (c) 2003-2021 John Willinsky
- * Distributed under the GNU GPL v3. For full terms see the file LICENSE.
- *
- * @brief Wrapper for COinS plugin.
- */
-
-require_once('CoinsPlugin.inc.php');
-return new CoinsPlugin();
-