diff --git a/src/Entity/Action.php b/src/Entity/Action.php
index f40b404..5a31637 100644
--- a/src/Entity/Action.php
+++ b/src/Entity/Action.php
@@ -7,12 +7,12 @@ use Illuminate\Support\Str;
 abstract class Action extends Entity
 {
     public function action(
-        $type = 'info',
-        $title = null,
-        $message = null,
-        $button = null,
-        $url = null,
-        $files = [],
+        string $type = 'info',
+        ?string $title = null,
+        ?string $message = null,
+        ?string $button = null,
+        ?string $url = null,
+        array $files = [],
     ) {
         return [
             'json' => [
@@ -23,16 +23,16 @@ abstract class Action extends Entity
     }
 
     public function file(
-        $contents,
-        $name = '',
-        $type = ''
+        string $contents,
+        string $name = '',
+        string $type = ''
     ) {
         return [
             'file' => compact('contents', 'name', 'type'),
         ];
     }
 
-    public function iframe($url, $expires = 240)
+    public function iframe(string $url, int $expires = 240)
     {
         $key = 'pilot_action_' . Str::random(10);
         $token = Str::random(40);
@@ -49,7 +49,7 @@ abstract class Action extends Entity
         ];
     }
 
-    public function link($url, $expires = 5)
+    public function link(string $url, int $expires = 5)
     {
         $key = 'pilot_action_' . Str::random(10);
         $token = Str::random(40);
@@ -66,7 +66,7 @@ abstract class Action extends Entity
         ];
     }
 
-    public function error($message)
+    public function error(string $message)
     {
         return [
             'json' => [
diff --git a/src/Entity/Entity.php b/src/Entity/Entity.php
index 5b50d95..dfadb0a 100644
--- a/src/Entity/Entity.php
+++ b/src/Entity/Entity.php
@@ -6,7 +6,7 @@ abstract class Entity
 {
     protected $slug = null;
 
-    public function __construct($slug = null)
+    public function __construct(?string $slug = null)
     {
         if (! is_null($slug)) {
             $this->slug = $slug;
diff --git a/src/Entity/Metric.php b/src/Entity/Metric.php
index b5a91f1..3ded7fe 100644
--- a/src/Entity/Metric.php
+++ b/src/Entity/Metric.php
@@ -62,12 +62,12 @@ abstract class Metric extends Widget
         ];
     }
 
-    public function filter($label, $value, callable $callback)
+    public function filter(string $label, $value, callable $callback)
     {
         return ['label' => $label, 'value' => $value, 'callback' => $callback];
     }
 
-    public function filters($filters)
+    public function filters(array $filters)
     {
         return $this->resolveFilter($filters);
     }
@@ -81,7 +81,7 @@ abstract class Metric extends Widget
         ];
     }
 
-    public function trend($values)
+    public function trend(array $values)
     {
         return [
             'type' => 'trend',
@@ -89,7 +89,7 @@ abstract class Metric extends Widget
         ];
     }
 
-    public function partition($values)
+    public function partition(array $values)
     {
         return [
             'type' => 'partition',
@@ -106,7 +106,7 @@ abstract class Metric extends Widget
         ];
     }
 
-    public function monitor($available)
+    public function monitor(bool $available)
     {
         return [
             'type' => 'monitor',
diff --git a/src/Pilot.php b/src/Pilot.php
index 56f3350..962b2cb 100644
--- a/src/Pilot.php
+++ b/src/Pilot.php
@@ -18,14 +18,14 @@ class Pilot
 
     }
 
-    public function authorize($token, $user_token)
+    public function authorize(string $token, string $user_token)
     {
         if ($token !== $user_token) {
             throw new \Exception('Unauthorized Pilot request');
         }
     }
 
-    public function form($slug, callable $function)
+    public function form(string $slug, callable $function)
     {
         $this->register('form', $slug, function () use ($function) {
             return [
@@ -36,17 +36,17 @@ class Pilot
         });
     }
 
-    public function action($slug, callable $function)
+    public function action(string $slug, callable $function)
     {
         $this->register('action', $slug, $function);
     }
 
-    public function metric($slug, callable $function)
+    public function metric(string $slug, callable $function)
     {
         $this->register('metric', $slug, $function);
     }
 
-    protected function register($type, $slug, callable $function)
+    protected function register(string $type, string $slug, callable $function)
     {
         $this->registry[$type][$slug] = $function;
     }
@@ -65,7 +65,7 @@ class Pilot
         return Response::error("Unknown {$type} {$slug}");
     }
 
-    public function resolveDependencies($slug, $function, $data, $files)
+    public function resolveDependencies(string $slug, $function, $data, $files)
     {
         $entries = isset($data['entries']) && is_array($data['entries']) ? $data['entries'] : [];
 
diff --git a/src/Response.php b/src/Response.php
index 0fb2544..04723c6 100644
--- a/src/Response.php
+++ b/src/Response.php
@@ -5,12 +5,12 @@ namespace Bluesquare\Pilot;
 class Response
 {
     public static function action(
-        $type = 'info',
-        $title = null,
-        $message = null,
-        $button = null,
-        $url = null,
-        $files = [],
+        string $type = 'info',
+        ?string $title = null,
+        ?string $message = null,
+        ?string $button = null,
+        ?string $url = null,
+        array $files = [],
     ) {
         return [
             'json' => [
@@ -20,7 +20,7 @@ class Response
         ];
     }
 
-    public static function error($message)
+    public static function error(string $message)
     {
         return [
             'json' => [
@@ -31,9 +31,9 @@ class Response
     }
 
     public static function file(
-        $contents,
-        $name = '',
-        $type = ''
+        string $contents,
+        string $name = '',
+        string $type = ''
     ) {
         return [
             'file' => compact('contents', 'name', 'type'),