diff --git a/classes/controllers/FrmAppController.php b/classes/controllers/FrmAppController.php
index 85acdb14da..14fc773e93 100644
--- a/classes/controllers/FrmAppController.php
+++ b/classes/controllers/FrmAppController.php
@@ -1630,8 +1630,7 @@ private static function is_our_callback_array( $callback ) {
 	private static function add_missing_tables() {
 		FrmAppHelper::permission_check( 'frm_view_forms' );
 
-		$inbox = new FrmInbox();
-		$error = $inbox->check_for_error();
+		$error = FrmInbox::check_for_error();
 
 		if ( ! $error || 'failed-to-create-tables' !== $error['key'] ) {
 			// Confirm the inbox item with this CTA exists.
diff --git a/classes/controllers/FrmFormsController.php b/classes/controllers/FrmFormsController.php
index 5f660b8102..910d578012 100644
--- a/classes/controllers/FrmFormsController.php
+++ b/classes/controllers/FrmFormsController.php
@@ -1212,8 +1212,7 @@ public static function display_forms_list( $params = array(), $message = '', $er
 			die();
 		}
 
-		$inbox = new FrmInbox();
-		$error = $inbox->check_for_error();
+		$error = FrmInbox::check_for_error();
 
 		if ( $error ) {
 			$show_messages = array( $error['subject'] . '. ' . $error['message'] );
diff --git a/classes/models/FrmInbox.php b/classes/models/FrmInbox.php
index 77372f2604..61915033e4 100644
--- a/classes/models/FrmInbox.php
+++ b/classes/models/FrmInbox.php
@@ -597,6 +597,7 @@ public static function check_for_error() {
 				return $message;
 			}
 		}
+
 		return false;
 	}
 }
diff --git a/composer.json b/composer.json
index 91ea72c682..48922e3189 100644
--- a/composer.json
+++ b/composer.json
@@ -39,7 +39,8 @@
 		"phpstan/extension-installer": "^1.3",
 		"slevomat/coding-standard": "~8.0",
 		"friendsofphp/php-cs-fixer": "^3.54",
-		"rector/rector": "^2.2.14"
+		"rector/rector": "^2.2.14",
+		"phpstan/phpstan-strict-rules": "^2.0"
 	},
 	"config": {
 		"allow-plugins": {
diff --git a/phpstan.neon b/phpstan.neon
index 02a1477ca9..e98bb9be35 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -273,6 +273,31 @@ parameters:
 		- message: '#function array_map expects#'
 		- message: '#expects resource#'
 		- message: '#might not be defined#'
-		- message: '#expects false, string given#'
 		- message: '#array given#'
 		- message: '#Cannot use \+\+ on int\|false#'
+		- message: '#Only booleans are allowed in an (elseif|if) condition#'
+		- message: '#Only booleans are allowed in a negated boolean#'
+		- message: '#Only booleans are allowed in a ternary operator condition#'
+		- message: '#Loose comparison via "(!=|==)" is not allowed#'
+		- message: '#Variable property access on#'
+		- message: '#does not call parent constructor#'
+		- message: '#Only booleans are allowed in (&&|\|\|)#'
+		- message: '#Variable method call on#'
+		- message: '#requires parameter \#[\d]* to be set#'
+		- message: '#array_filter\(\) requires parameter \#2 to be passed to avoid loose comparison semantics.#'
+		- message: '#Static call to __construct\(\) is only allowed on a parent class in the constructor#'
+		- message: '#Variable static method call on#'
+		-
+			message: '#should be contravariant with#'
+			paths:
+				- classes/helpers/FrmFormsListHelper.php
+				- classes/models/FrmInstallerSkin.php
+		- '#Construct empty\(\) is not allowed. Use more strict comparison#'
+		-
+			message: '#Foreach overwrites \$ip with its value variable.#'
+			path: classes/helpers/FrmAppHelper.php
+		-
+			message: '#Only numeric types are allowed#'
+			paths:
+				- classes/helpers/FrmCSVExportHelper.php
+				- classes/models/FrmStyle.php