diff --git a/src/Contract/Translator.php b/src/Contract/Translator.php
index 85ab515..c0dd1ff 100644
--- a/src/Contract/Translator.php
+++ b/src/Contract/Translator.php
@@ -10,25 +10,25 @@ interface Translator
     /**
      * Translate a message
      *
-     * @param string $message
-     * @param string $context Message context
+     * @param string  $message
+     * @param ?string $context Message context
      *
      * @return string Translated message or original message if no translation is found
      */
-    public function translate($message, $context = null);
+    public function translate(string $message, ?string $context = null): string;
 
     /**
      * Translate a message in the given domain
      *
      * If no translation is found in the specified domain, the translation is also searched for in the default domain.
      *
-     * @param string $domain
-     * @param string $message
-     * @param string $context Message context
+     * @param string  $domain
+     * @param string  $message
+     * @param ?string $context Message context
      *
      * @return string Translated message or original message if no translation is found
      */
-    public function translateInDomain($domain, $message, $context = null);
+    public function translateInDomain(string $domain, string $message, ?string $context = null): string;
 
     /**
      * Translate a plural message
@@ -36,14 +36,14 @@ public function translateInDomain($domain, $message, $context = null);
      * The returned message is based on the given number to decide between the singular and plural forms.
      * That is also the case if no translation is found.
      *
-     * @param string $singular Singular message
-     * @param string $plural   Plural message
-     * @param int    $number   Number to decide between the returned singular and plural forms
-     * @param string $context  Message context
+     * @param string  $singular Singular message
+     * @param string  $plural   Plural message
+     * @param int     $number   Number to decide between the returned singular and plural forms
+     * @param ?string $context  Message context
      *
      * @return string Translated message or original message if no translation is found
      */
-    public function translatePlural($singular, $plural, $number, $context = null);
+    public function translatePlural(string $singular, string $plural, int $number, ?string $context = null): string;
 
     /**
      * Translate a plural message in the given domain
@@ -53,13 +53,19 @@ public function translatePlural($singular, $plural, $number, $context = null);
      * The returned message is based on the given number to decide between the singular and plural forms.
      * That is also the case if no translation is found.
      *
-     * @param string $domain
-     * @param string $singular Singular message
-     * @param string $plural   Plural message
-     * @param int    $number   Number to decide between the returned singular and plural forms
-     * @param string $context  Message context
+     * @param string  $domain
+     * @param string  $singular Singular message
+     * @param string  $plural   Plural message
+     * @param int     $number   Number to decide between the returned singular and plural forms
+     * @param ?string $context  Message context
      *
      * @return string Translated message or original message if no translation is found
      */
-    public function translatePluralInDomain($domain, $singular, $plural, $number, $context = null);
+    public function translatePluralInDomain(
+        string $domain,
+        string $singular,
+        string $plural,
+        int $number,
+        ?string $context = null
+    ): string;
 }