diff --git a/classes/plugin-template.php b/classes/plugin-template.php
index ad6d07ee0..12437525b 100644
--- a/classes/plugin-template.php
+++ b/classes/plugin-template.php
@@ -5,53 +5,57 @@ abstract class PluginTemplate {
 	/** @var PDO $pdo */
 	protected $pdo;
 
-	abstract function init(PluginHost $host);
+	abstract function init(PluginHost $host) : void;
 
-	abstract function about();
+	/** @return array<float|string|bool> */
+	abstract function about() : array;
 	// return array(1.0, "plugin", "No description", "No author", false);
 
 	function __construct() {
 		$this->pdo = Db::pdo();
 	}
 
-	function flags() {
+	/** @return array<string,int> */
+	function flags() : array {
 		/* associative array, possible keys:
 			needs_curl = boolean
 		*/
 		return array();
 	}
 
-	function is_public_method($method) {
+	function is_public_method(string $method) : bool {
 		return false;
 	}
 
-	function csrf_ignore($method) {
+	function csrf_ignore(string $method) : bool {
 		return false;
 	}
 
-	function get_js() {
+	function get_js() : string {
 		return "";
 	}
 
-	function get_prefs_js() {
+	function get_prefs_js() : string {
 		return "";
 	}
 
-	function api_version() {
+	function api_version() : int {
 		return Plugin::API_VERSION_COMPAT;
 	}
 
 	/* gettext-related helpers */
 
-	function __($msgid) {
+	function __(string $msgid) : string {
+		/** @var Plugin $this -- this is a strictly template-related hack */
 		return _dgettext(PluginHost::object_to_domain($this), $msgid);
 	}
 
-	function _ngettext($singular, $plural, $number) {
+	function _ngettext(string $singular, string $plural, int $number) : string {
+		/** @var Plugin $this -- this is a strictly template-related hack */
 		return _dngettext(PluginHost::object_to_domain($this), $singular, $plural, $number);
 	}
 
-	function T_sprintf() {
+	function T_sprintf() : string {
 		$args = func_get_args();
 		$msgid = array_shift($args);
 
diff --git a/classes/plugin.php b/classes/plugin.php
index 1b6702d72..08a122023 100644
--- a/classes/plugin.php
+++ b/classes/plugin.php
@@ -5,53 +5,57 @@ abstract class Plugin {
 	/** @var PDO $pdo */
 	protected $pdo;
 
-	abstract function init(PluginHost $host);
+	abstract function init(PluginHost $host) : void;
 
-	abstract function about();
+	/** @return array<float|string|bool> */
+	abstract function about() : array;
 	// return array(1.0, "plugin", "No description", "No author", false);
 
 	function __construct() {
 		$this->pdo = Db::pdo();
 	}
 
-	function flags() {
+	/** @return array<string,int> */
+	function flags() : array {
 		/* associative array, possible keys:
 			needs_curl = boolean
 		*/
 		return array();
 	}
 
-	function is_public_method($method) {
+	function is_public_method(string $method) : bool {
 		return false;
 	}
 
-	function csrf_ignore($method) {
+	function csrf_ignore(string $method) : bool {
 		return false;
 	}
 
-	function get_js() {
+	function get_js() : string {
 		return "";
 	}
 
-	function get_prefs_js() {
+	function get_prefs_js() : string {
 		return "";
 	}
 
-	function api_version() {
+	function api_version() : int {
 		return Plugin::API_VERSION_COMPAT;
 	}
 
 	/* gettext-related helpers */
 
-	function __($msgid) {
+	function __(string $msgid) : string {
+		/** @var Plugin $this -- this is a strictly template-related hack */
 		return _dgettext(PluginHost::object_to_domain($this), $msgid);
 	}
 
-	function _ngettext($singular, $plural, $number) {
+	function _ngettext(string $singular, string $plural, int $number) : string {
+		/** @var Plugin $this -- this is a strictly template-related hack */
 		return _dngettext(PluginHost::object_to_domain($this), $singular, $plural, $number);
 	}
 
-	function T_sprintf() {
+	function T_sprintf() : string {
 		$args = func_get_args();
 		$msgid = array_shift($args);