diff --git a/.travis.yml b/.travis.yml
index 578ee24..873441f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,13 +1,18 @@
 language: php
 
 php:
-    - 5.3
     - 5.4
     - 5.5
+    - 5.6
+    - 7.0
+
+env:
+  matrix:
+    - PREFER_LOWEST="--prefer-lowest"
+    - PREFER_LOWEST=""
 
 before_script:
-    - curl -s http://getcomposer.org/installer | php
-    - php composer.phar --dev install
+  - composer update --prefer-source PREFER_LOWEST
 
 script:
   - bin/phpspec run -v -f pretty
diff --git a/spec/Coduo/ToString/StringSpec.php b/spec/Coduo/ToString/StringConverterSpec.php
similarity index 82%
rename from spec/Coduo/ToString/StringSpec.php
rename to spec/Coduo/ToString/StringConverterSpec.php
index fd9b53b..2deea4c 100644
--- a/spec/Coduo/ToString/StringSpec.php
+++ b/spec/Coduo/ToString/StringConverterSpec.php
@@ -12,12 +12,12 @@ public function __toString()
     }
 }
 
-class StringSpec extends ObjectBehavior
+class StringConverterSpec extends ObjectBehavior
 {
     /**
      * @dataProvider positiveConversionExamples
      */
-    function it_convert_values_to_string($value, $expectedValue)
+    function it_converts_values_to_string($value, $expectedValue)
     {
         $this->beConstructedWith($value);
         $this->__toString()->shouldReturn($expectedValue);
@@ -36,13 +36,13 @@ function positiveConversionExamples()
         );
     }
 
-    function it_convert_double_to_string_for_specific_locale()
+    function it_converts_double_to_string_for_specific_locale()
     {
         $this->beConstructedWith(1.1, 'pl');
         $this->__toString()->shouldReturn('1,1');
     }
 
-    function it_convert_resource_to_string()
+    function it_converts_resource_to_string()
     {
         $resource = fopen(sys_get_temp_dir() . "/foo", "w");
         $this->beConstructedWith($resource);
diff --git a/src/Coduo/ToString/String.php b/src/Coduo/ToString/StringConverter.php
similarity index 98%
rename from src/Coduo/ToString/String.php
rename to src/Coduo/ToString/StringConverter.php
index 32e4084..e4292b7 100644
--- a/src/Coduo/ToString/String.php
+++ b/src/Coduo/ToString/StringConverter.php
@@ -2,7 +2,7 @@
 
 namespace Coduo\ToString;
 
-class String
+class StringConverter
 {
     /**
      * @var mixed