diff --git a/composer.json b/composer.json
index bd58070..34ee9f5 100644
--- a/composer.json
+++ b/composer.json
@@ -12,10 +12,10 @@
       "psr-4": {"JJWare\\Utils\\Option\\": "src"}
     },
     "require": {
-      "php": ">=7.1.0"
+      "php": ">=7.0.0"
     },
     "require-dev": {
-      "phpUnit/phpUnit": "^7.1"
+      "phpUnit/phpUnit": "^6.5"
     }
   }
   
\ No newline at end of file
diff --git a/src/None.php b/src/None.php
index 413861e..0cafc71 100644
--- a/src/None.php
+++ b/src/None.php
@@ -28,7 +28,7 @@ public function getOrThrow(callable $f)
         throw call_user_func($f);
     }
 
-    public function forEach(callable $f): void
+    public function forEach(callable $f)
     {
         // do nothing
     }
diff --git a/src/Option.php b/src/Option.php
index 5e5d645..10ac32b 100644
--- a/src/Option.php
+++ b/src/Option.php
@@ -9,7 +9,7 @@ public abstract function map(callable $f): Option;
     public abstract function getOrElseGet(callable $f);
     public abstract function getOrElse($default);
     public abstract function getOrThrow(callable $f);
-    public abstract function forEach(callable $f): void;
+    public abstract function forEach(callable $f);
     public abstract function isSome(): bool;
     public abstract function isNone(): bool;
 
diff --git a/src/Some.php b/src/Some.php
index a9bcc42..2ef778a 100644
--- a/src/Some.php
+++ b/src/Some.php
@@ -38,7 +38,7 @@ public function getOrThrow(callable $f)
         return $this->value;
     }
 
-    public function forEach(callable $f): void
+    public function forEach(callable $f)
     {
         call_user_func($f, $this->value);
     }