diff --git a/.travis.yml b/.travis.yml
index bcaf682ce..d1c701729 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,6 +3,7 @@ php:
   - 5.6
   - 5.5
   - 5.4
+  - 5.3
 install:
   - composer self-update
   - composer install
diff --git a/README.md b/README.md
index 15d4379af..b3dbaf5fa 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@ Password: `demo`
 
 ## Installing
 
-Shaarli requires php 5.4. `php-gd` is optional and provides thumbnail resizing.
+Shaarli requires PHP 5.3. `php-gd` is optional and provides thumbnail resizing.
 
  * Download the latest stable release from https://github.com/shaarli/Shaarli/releases
  * Unpack the archive in a directory on your web server
diff --git a/application/Config.php b/application/Config.php
index 0b01b5246..ec799d7f7 100755
--- a/application/Config.php
+++ b/application/Config.php
@@ -19,10 +19,10 @@
 function writeConfig($config, $isLoggedIn)
 {
     // These fields are required in configuration.
-    $MANDATORY_FIELDS = [
+    $MANDATORY_FIELDS = array(
         'login', 'hash', 'salt', 'timezone', 'title', 'titleLink',
         'redirector', 'disablesessionprotection', 'privateLinkByDefault'
-    ];
+    );
 
     if (!isset($config['config']['CONFIG_FILE'])) {
         throw new MissingFieldConfigException('CONFIG_FILE');
@@ -126,4 +126,4 @@ public function __construct()
     {
         $this->message = 'You are not authorized to alter config.';
     }
-}
\ No newline at end of file
+}
diff --git a/application/TimeZone.php b/application/TimeZone.php
new file mode 100644
index 000000000..ccbef918b
--- /dev/null
+++ b/application/TimeZone.php
@@ -0,0 +1,110 @@
+<?php
+/**
+ * Generates the timezone selection form and JavaScript.
+ *
+ * Note: 'UTC/UTC' is mapped to 'UTC' to form a valid option
+ *
+ * Example: preselect Europe/Paris
+ *  list($htmlform, $js) = templateTZform('Europe/Paris');
+ *
+ * @param string $preselected_timezone preselected timezone (optional)
+ *
+ * @return an array containing the generated HTML form and Javascript code
+ **/
+function generateTimeZoneForm($preselected_timezone='')
+{
+    // Select the first available timezone if no preselected value is passed
+    if ($preselected_timezone == '') {
+        $l = timezone_identifiers_list();
+        $preselected_timezone = $l[0];
+    }
+
+    // Try to split the provided timezone
+    $spos = strpos($preselected_timezone, '/');
+    $pcontinent = substr($preselected_timezone, 0, $spos);
+    $pcity = substr($preselected_timezone, $spos+1);
+
+    // Display config form:
+    $timezone_form = '';
+    $timezone_js = '';
+
+    // The list is in the form 'Europe/Paris', 'America/Argentina/Buenos_Aires'...
+    // We split the list in continents/cities.
+    $continents = array();
+    $cities = array();
+
+    // TODO: use a template to generate the HTML/Javascript form
+
+    foreach (timezone_identifiers_list() as $tz) {
+        if ($tz == 'UTC') {
+            $tz = 'UTC/UTC';
+        }
+        $spos = strpos($tz, '/');
+
+        if ($spos !== false) {
+            $continent = substr($tz, 0, $spos);
+            $city = substr($tz, $spos+1);
+            $continents[$continent] = 1;
+
+            if (!isset($cities[$continent])) {
+                $cities[$continent] = '';
+            }
+            $cities[$continent] .= '<option value="'.$city.'"';
+            if ($pcity == $city) {
+                $cities[$continent] .= ' selected="selected"';
+            }
+            $cities[$continent] .= '>'.$city.'</option>';
+        }
+    }
+
+    $continents_html = '';
+    $continents = array_keys($continents);
+
+    foreach ($continents as $continent) {
+        $continents_html .= '<option  value="'.$continent.'"';
+        if ($pcontinent == $continent) {
+            $continents_html .= ' selected="selected"';
+        }
+        $continents_html .= '>'.$continent.'</option>';
+    }
+
+    // Timezone selection form
+    $timezone_form = 'Continent:';
+    $timezone_form .= '<select name="continent" id="continent" onChange="onChangecontinent();">';
+    $timezone_form .= $continents_html.'</select>';
+    $timezone_form .= '&nbsp;&nbsp;&nbsp;&nbsp;City:';
+    $timezone_form .= '<select name="city" id="city">'.$cities[$pcontinent].'</select><br />';
+
+    // Javascript handler - updates the city list when the user selects a continent
+    $timezone_js = '<script>';
+    $timezone_js .= 'function onChangecontinent() {';
+    $timezone_js .= 'document.getElementById("city").innerHTML =';
+    $timezone_js .= ' citiescontinent[document.getElementById("continent").value]; }';
+    $timezone_js .= 'var citiescontinent = '.json_encode($cities).';';
+    $timezone_js .= '</script>';
+
+    return array($timezone_form, $timezone_js);
+}
+
+/**
+ * Tells if a continent/city pair form a valid timezone
+ *
+ * Note: 'UTC/UTC' is mapped to 'UTC'
+ *
+ * @param string $continent the timezone continent
+ * @param string $city      the timezone city
+ *
+ * @return whether continent/city is a valid timezone
+ */
+function isTimeZoneValid($continent, $city)
+{
+    if ($continent == 'UTC' && $city == 'UTC') {
+        return true;
+    }
+
+    return in_array(
+        $continent.'/'.$city,
+        timezone_identifiers_list()
+    );
+}
+?>
diff --git a/application/Utils.php b/application/Utils.php
index 658b97bc2..cd4724fa3 100644
--- a/application/Utils.php
+++ b/application/Utils.php
@@ -48,7 +48,7 @@ function endsWith($haystack, $needle, $case=true)
  */
 function nl2br_escaped($html)
 {
-    return str_replace('>','&gt;',str_replace('<','&lt;',nl2br($html)));
+    return str_replace('>', '&gt;', str_replace('<', '&lt;', nl2br($html)));
 }
 
 /**
@@ -117,3 +117,24 @@ function generateLocation($referer, $host, $loopTerms = array())
 
     return $final_referer;
 }
+
+/**
+ * Checks the PHP version to ensure Shaarli can run
+ *
+ * @param string $minVersion minimum PHP required version
+ * @param string $curVersion current PHP version (use PHP_VERSION)
+ *
+ * @throws Exception    the PHP version is not supported
+ */
+function checkPHPVersion($minVersion, $curVersion)
+{
+    if (version_compare($curVersion, $minVersion) < 0) {
+        throw new Exception(
+            'Your PHP version is obsolete!'
+            .' Shaarli requires at least PHP '.$minVersion.', and thus cannot run.'
+            .' Your PHP version has known security vulnerabilities and should be'
+            .' updated as soon as possible.'
+        );
+    }
+}
+?>
diff --git a/index.php b/index.php
index bf0b99e04..6d3fbd396 100644
--- a/index.php
+++ b/index.php
@@ -3,7 +3,7 @@
 // The personal, minimalist, super-fast, no-database Delicious clone. By sebsauvage.net
 // http://sebsauvage.net/wiki/doku.php?id=php:shaarli
 // Licence: http://www.opensource.org/licenses/zlib-license.php
-// Requires: PHP 5.1.x  (but autocomplete fields will only work if you have PHP 5.2.x)
+// Requires: PHP 5.3.x
 // -----------------------------------------------------------------------------------------------
 // NEVER TRUST IN PHP.INI
 // Some hosts do not define a default timezone in php.ini,
@@ -59,7 +59,6 @@
 ini_set('memory_limit', '128M');  // Try to set max upload file size and read (May not work on some hosts).
 ini_set('post_max_size', '16M');
 ini_set('upload_max_filesize', '16M');
-checkphpversion();
 error_reporting(E_ALL^E_WARNING);  // See all error except warnings.
 //error_reporting(-1); // See all errors (for debugging only)
 
@@ -70,9 +69,19 @@
 
 // Shaarli library
 require_once 'application/LinkDB.php';
+require_once 'application/TimeZone.php';
 require_once 'application/Utils.php';
 require_once 'application/Config.php';
 
+// Ensure the PHP version is supported
+try {
+    checkPHPVersion('5.3', PHP_VERSION);
+} catch(Exception $e) {
+    header('Content-Type: text/plain; charset=utf-8');
+    echo $e->getMessage();
+    exit;
+}
+
 include "inc/rain.tpl.class.php"; //include Rain TPL
 raintpl::$tpl_dir = $GLOBALS['config']['RAINTPL_TPL']; // template directory
 raintpl::$cache_dir = $GLOBALS['config']['RAINTPL_TMP']; // cache directory
@@ -164,21 +173,7 @@ function setup_login_state() {
 
 	return $userIsLoggedIn;
 }
-//==================================================================================================
 $userIsLoggedIn = setup_login_state();
-//==================================================================================================
-//==================================================================================================
-
-// Check PHP version
-function checkphpversion()
-{
-    if (version_compare(PHP_VERSION, '5.1.0') < 0)
-    {
-        header('Content-Type: text/plain; charset=utf-8');
-        echo 'Your PHP version is obsolete! Shaarli requires at least php 5.1.0, and thus cannot run. Sorry. Your PHP version has known security vulnerabilities and should be updated as soon as possible.';
-        exit;
-    }
-}
 
 // Checks if an update is available for Shaarli.
 // (at most once a day, and only for registered user.)
@@ -982,7 +977,7 @@ function showDaily()
         $linksToDisplay = $LINKSDB->filterDay($day);
     } catch (Exception $exc) {
         error_log($exc);
-        $linksToDisplay = [];
+        $linksToDisplay = array();
     }
 
     // We pre-format some fields for proper output.
@@ -1288,7 +1283,7 @@ function renderPage()
             if (!tokenOk($_POST['token'])) die('Wrong token.'); // Go away!
             $tz = 'UTC';
             if (!empty($_POST['continent']) && !empty($_POST['city']))
-                if (isTZvalid($_POST['continent'],$_POST['city']))
+                if (isTimeZoneValid($_POST['continent'],$_POST['city']))
                     $tz = $_POST['continent'].'/'.$_POST['city'];
             $GLOBALS['timezone'] = $tz;
             $GLOBALS['title']=$_POST['title'];
@@ -1322,8 +1317,8 @@ function renderPage()
             $PAGE->assign('token',getToken());
             $PAGE->assign('title', empty($GLOBALS['title']) ? '' : $GLOBALS['title'] );
             $PAGE->assign('redirector', empty($GLOBALS['redirector']) ? '' : $GLOBALS['redirector'] );
-            list($timezone_form,$timezone_js) = templateTZform($GLOBALS['timezone']);
-            $PAGE->assign('timezone_form',$timezone_form); // FIXME: Put entire tz form generation in template?
+            list($timezone_form, $timezone_js) = generateTimeZoneForm($GLOBALS['timezone']);
+            $PAGE->assign('timezone_form', $timezone_form);
             $PAGE->assign('timezone_js',$timezone_js);
             $PAGE->renderPage('configure');
             exit;
@@ -2059,9 +2054,11 @@ function install()
     if (!empty($_POST['setlogin']) && !empty($_POST['setpassword']))
     {
         $tz = 'UTC';
-        if (!empty($_POST['continent']) && !empty($_POST['city']))
-            if (isTZvalid($_POST['continent'],$_POST['city']))
+        if (!empty($_POST['continent']) && !empty($_POST['city'])) {
+            if (isTimeZoneValid($_POST['continent'], $_POST['city'])) {
                 $tz = $_POST['continent'].'/'.$_POST['city'];
+            }
+        }
         $GLOBALS['timezone'] = $tz;
         // Everything is ok, let's create config file.
         $GLOBALS['login'] = $_POST['setlogin'];
@@ -2087,8 +2084,11 @@ function install()
     }
 
     // Display config form:
-    list($timezone_form,$timezone_js) = templateTZform();
-    $timezone_html=''; if ($timezone_form!='') $timezone_html='<tr><td><b>Timezone:</b></td><td>'.$timezone_form.'</td></tr>';
+    list($timezone_form, $timezone_js) = generateTimeZoneForm();
+    $timezone_html = '';
+    if ($timezone_form != '') {
+        $timezone_html = '<tr><td><b>Timezone:</b></td><td>'.$timezone_form.'</td></tr>';
+    }
 
     $PAGE = new pageBuilder;
     $PAGE->assign('timezone_html',$timezone_html);
@@ -2097,67 +2097,6 @@ function install()
     exit;
 }
 
-// Generates the timezone selection form and JavaScript.
-// Input: (optional) current timezone (can be 'UTC/UTC'). It will be pre-selected.
-// Output: array(html,js)
-// Example: list($htmlform,$js) = templateTZform('Europe/Paris');  // Europe/Paris pre-selected.
-// Returns array('','') if server does not support timezones list. (e.g. PHP 5.1 on free.fr)
-function templateTZform($ptz=false)
-{
-    if (function_exists('timezone_identifiers_list')) // because of old PHP version (5.1) which can be found on free.fr
-    {
-        // Try to split the provided timezone.
-        if ($ptz==false) { $l=timezone_identifiers_list(); $ptz=$l[0]; }
-        $spos=strpos($ptz,'/'); $pcontinent=substr($ptz,0,$spos); $pcity=substr($ptz,$spos+1);
-
-        // Display config form:
-        $timezone_form = '';
-        $timezone_js = '';
-        // The list is in the form "Europe/Paris", "America/Argentina/Buenos_Aires"...
-        // We split the list in continents/cities.
-        $continents = array();
-        $cities = array();
-        foreach(timezone_identifiers_list() as $tz)
-        {
-            if ($tz=='UTC') $tz='UTC/UTC';
-            $spos = strpos($tz,'/');
-            if ($spos!==false)
-            {
-                $continent=substr($tz,0,$spos); $city=substr($tz,$spos+1);
-                $continents[$continent]=1;
-                if (!isset($cities[$continent])) $cities[$continent]='';
-                $cities[$continent].='<option value="'.$city.'"'.($pcity==$city?' selected':'').'>'.$city.'</option>';
-            }
-        }
-        $continents_html = '';
-        $continents = array_keys($continents);
-        foreach($continents as $continent)
-            $continents_html.='<option  value="'.$continent.'"'.($pcontinent==$continent?' selected':'').'>'.$continent.'</option>';
-        $cities_html = $cities[$pcontinent];
-        $timezone_form = "Continent: <select name=\"continent\" id=\"continent\" onChange=\"onChangecontinent();\">${continents_html}</select>";
-        $timezone_form .= "&nbsp;&nbsp;&nbsp;&nbsp;City: <select name=\"city\" id=\"city\">${cities[$pcontinent]}</select><br />";
-        $timezone_js = "<script>";
-        $timezone_js .= "function onChangecontinent(){document.getElementById(\"city\").innerHTML = citiescontinent[document.getElementById(\"continent\").value];}";
-        $timezone_js .= "var citiescontinent = ".json_encode($cities).";" ;
-        $timezone_js .= "</script>" ;
-        return array($timezone_form,$timezone_js);
-    }
-    return array('','');
-}
-
-// Tells if a timezone is valid or not.
-// If not valid, returns false.
-// If system does not support timezone list, returns false.
-function isTZvalid($continent,$city)
-{
-    $tz = $continent.'/'.$city;
-    if (function_exists('timezone_identifiers_list')) // because of old PHP version (5.1) which can be found on free.fr
-    {
-        if (in_array($tz, timezone_identifiers_list())) // it's a valid timezone?
-                    return true;
-    }
-    return false;
-}
 if (!function_exists('json_encode')) {
     function json_encode($data) {
         switch ($type = gettype($data)) {
diff --git a/tests/ConfigTest.php b/tests/ConfigTest.php
index 4279c57e5..a239d8b7d 100755
--- a/tests/ConfigTest.php
+++ b/tests/ConfigTest.php
@@ -18,7 +18,7 @@ class ConfigTest extends PHPUnit_Framework_TestCase
      */
     public function setUp()
     {
-        self::$_configFields = [
+        self::$_configFields = array(
             'login' => 'login',
             'hash' => 'hash',
             'salt' => 'salt',
@@ -28,13 +28,13 @@ public function setUp()
             'redirector' => '',
             'disablesessionprotection' => false,
             'privateLinkByDefault' => false,
-            'config' => [
+            'config' => array(
                 'CONFIG_FILE' => 'tests/config.php',
                 'DATADIR' => 'tests',
                 'config1' => 'config1data',
                 'config2' => 'config2data',
-            ]
-        ];
+            )
+        );
     }
 
     /**
@@ -174,4 +174,4 @@ public function testMergeDeprecatedConfigNoFile()
         include self::$_configFields['config']['CONFIG_FILE'];
         $this->assertEquals(self::$_configFields['login'], $GLOBALS['login']);
     }
-}
\ No newline at end of file
+}
diff --git a/tests/LinkDBTest.php b/tests/LinkDBTest.php
index d34ea4f56..504c81901 100644
--- a/tests/LinkDBTest.php
+++ b/tests/LinkDBTest.php
@@ -228,12 +228,12 @@ public function testCountHiddenPublic()
     public function testDays()
     {
         $this->assertEquals(
-            ['20121206', '20130614', '20150310'],
+            array('20121206', '20130614', '20150310'),
             self::$publicLinkDB->days()
         );
 
         $this->assertEquals(
-            ['20121206', '20130614', '20141125', '20150310'],
+            array('20121206', '20130614', '20141125', '20150310'),
             self::$privateLinkDB->days()
         );
     }
@@ -269,7 +269,7 @@ public function testGetUnknownLinkFromURL()
     public function testAllTags()
     {
         $this->assertEquals(
-            [
+            array(
                 'web' => 3,
                 'cartoon' => 2,
                 'gnu' => 2,
@@ -279,12 +279,12 @@ public function testAllTags()
                 'software' => 1,
                 'stallman' => 1,
                 'free' => 1
-            ],
+            ),
             self::$publicLinkDB->allTags()
         );
 
         $this->assertEquals(
-            [
+            array(
                 'web' => 4,
                 'cartoon' => 3,
                 'gnu' => 2,
@@ -298,7 +298,7 @@ public function testAllTags()
                 'w3c' => 1,
                 'css' => 1,
                 'Mercurial' => 1
-            ],
+            ),
             self::$privateLinkDB->allTags()
         );
     }
diff --git a/tests/TimeZoneTest.php b/tests/TimeZoneTest.php
new file mode 100644
index 000000000..f3de39139
--- /dev/null
+++ b/tests/TimeZoneTest.php
@@ -0,0 +1,83 @@
+<?php
+/**
+ * TimeZone's tests
+ */
+
+require_once 'application/TimeZone.php';
+
+/**
+ * Unitary tests for timezone utilities
+ */
+class TimeZoneTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * Generate a timezone selection form
+     */
+    public function testGenerateTimeZoneForm()
+    {
+        $generated = generateTimeZoneForm();
+
+        // HTML form
+        $this->assertStringStartsWith('Continent:<select', $generated[0]);
+        $this->assertContains('selected="selected"', $generated[0]);
+        $this->assertStringEndsWith('</select><br />', $generated[0]);
+
+        // Javascript handler
+        $this->assertStringStartsWith('<script>', $generated[1]);
+        $this->assertContains(
+            '<option value=\"Bermuda\">Bermuda<\/option>',
+            $generated[1]
+        );
+        $this->assertStringEndsWith('</script>', $generated[1]);
+    }
+
+    /**
+     * Generate a timezone selection form, with a preselected timezone
+     */
+    public function testGenerateTimeZoneFormPreselected()
+    {
+        $generated = generateTimeZoneForm('Antarctica/Syowa');
+
+        // HTML form
+        $this->assertStringStartsWith('Continent:<select', $generated[0]);
+        $this->assertContains(
+            'value="Antarctica" selected="selected"',
+            $generated[0]
+        );
+        $this->assertContains(
+            'value="Syowa" selected="selected"',
+            $generated[0]
+        );
+        $this->assertStringEndsWith('</select><br />', $generated[0]);
+
+
+        // Javascript handler
+        $this->assertStringStartsWith('<script>', $generated[1]);
+        $this->assertContains(
+            '<option value=\"Bermuda\">Bermuda<\/option>',
+            $generated[1]
+        );
+        $this->assertStringEndsWith('</script>', $generated[1]);
+    }
+
+    /**
+     * Check valid timezones
+     */
+    public function testValidTimeZone()
+    {
+        $this->assertTrue(isTimeZoneValid('America', 'Argentina/Ushuaia'));
+        $this->assertTrue(isTimeZoneValid('Europe', 'Oslo'));
+        $this->assertTrue(isTimeZoneValid('UTC', 'UTC'));
+    }
+
+    /**
+     * Check invalid timezones
+     */
+    public function testInvalidTimeZone()
+    {
+        $this->assertFalse(isTimeZoneValid('CEST', 'CEST'));
+        $this->assertFalse(isTimeZoneValid('Europe', 'Atlantis'));
+        $this->assertFalse(isTimeZoneValid('Middle_Earth', 'Moria'));
+    }
+}
+?>
diff --git a/tests/UtilsTest.php b/tests/UtilsTest.php
index 8355c7f81..28e15f5a6 100644
--- a/tests/UtilsTest.php
+++ b/tests/UtilsTest.php
@@ -109,7 +109,7 @@ public function testGenerateLocation() {
      */
     public function testGenerateLocationLoop() {
         $ref = 'http://localhost/?test';
-        $this->assertEquals('?', generateLocation($ref, 'localhost', ['test']));
+        $this->assertEquals('?', generateLocation($ref, 'localhost', array('test')));
     }
 
     /**
@@ -119,4 +119,36 @@ public function testGenerateLocationOut() {
         $ref = 'http://somewebsite.com/?test';
         $this->assertEquals('?', generateLocation($ref, 'localhost'));
     }
+
+    /**
+     * Check supported PHP versions
+     */
+    public function testCheckSupportedPHPVersion()
+    {
+        $minVersion = '5.3';
+        checkPHPVersion($minVersion, '5.4.32');
+        checkPHPVersion($minVersion, '5.5');
+        checkPHPVersion($minVersion, '5.6.10');
+    }
+
+    /**
+     * Check a unsupported PHP version
+     * @expectedException              Exception
+     * @expectedExceptionMessageRegExp /Your PHP version is obsolete/
+     */
+    public function testCheckSupportedPHPVersion51()
+    {
+        checkPHPVersion('5.3', '5.1.0');
+    }
+
+    /**
+     * Check another unsupported PHP version
+     * @expectedException              Exception
+     * @expectedExceptionMessageRegExp /Your PHP version is obsolete/
+     */
+    public function testCheckSupportedPHPVersion52()
+    {
+        checkPHPVersion('5.3', '5.2');
+    }
 }
+?>