diff --git a/.travis.yml b/.travis.yml
index 574ac5db..9897777d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,6 @@
 language: php
 
 php:
-  - 5.5
   - 5.6
   - 7.0
   - 7.1
diff --git a/README.md b/README.md
index 3f1892b7..9de59dff 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ PhpSpreadsheet is a library written in pure PHP and providing a set of classes t
 
 ## Requirements
 
- * PHP version 5.5 or higher
+ * PHP version 5.6 or higher
  * PHP extension php_zip enabled (required if you need PhpSpreadsheet to handle .xlsx .ods or .gnumeric files)
  * PHP extension php_xml enabled
  * PHP extension php_gd2 enabled (optional, but required for exact column width autocalculation)
diff --git a/composer.json b/composer.json
index ae64f5cc..5e96be6a 100644
--- a/composer.json
+++ b/composer.json
@@ -23,7 +23,7 @@
         }
     ],
     "require": {
-        "php": "^5.5|^7.0",
+        "php": "^5.6|^7.0",
         "ext-mbstring": "*",
         "ext-iconv": "*",
         "ext-xml": "*",
diff --git a/docs/index.md b/docs/index.md
index 430af4e3..3d4a01ba 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -12,7 +12,7 @@ spreadsheet file formats, like Excel and LibreOffice Calc.
 
 The following software is required to develop using PhpSpreadsheet:
 
--   PHP version 5.5 or newer
+-   PHP version 5.6 or newer
 -   PHP extension php\_zip enabled (see
     [FAQ](./faq.md#php-complains-about-ziparchive-not-being-found))
 -   PHP extension php\_xml enabled
diff --git a/samples/index.php b/samples/index.php
index 748ec6f9..8347ea32 100644
--- a/samples/index.php
+++ b/samples/index.php
@@ -3,7 +3,7 @@
 require_once 'Header.php';
 
 $requirements = [
-    'PHP 5.5.0' => version_compare(phpversion(), '5.5.0', '>='),
+    'PHP 5.6.0' => version_compare(phpversion(), '5.6.0', '>='),
     'PHP extension XML' => extension_loaded('xml'),
     'PHP extension xmlwriter' => extension_loaded('xmlwriter'),
     'PHP extension mbstring' => extension_loaded('mbstring'),