diff --git a/install-dev/classes/controllerHttp.php b/install-dev/classes/controllerHttp.php
index aaffad35a..99aa236f6 100644
--- a/install-dev/classes/controllerHttp.php
+++ b/install-dev/classes/controllerHttp.php
@@ -354,6 +354,11 @@ abstract class InstallControllerHttp
 		return $this->language->getInformation('support');
 	}
 
+	public function getDocumentationUpgradeLink()
+	{
+		return $this->language->getInformation('documentation_upgrade', true);
+	}
+
 	/**
 	 * Send AJAX response in JSON format {success: bool, message: string}
 	 *
diff --git a/install-dev/controllers/http/welcome.php b/install-dev/controllers/http/welcome.php
index 40312f4ff..3966b389e 100644
--- a/install-dev/controllers/http/welcome.php
+++ b/install-dev/controllers/http/welcome.php
@@ -68,6 +68,17 @@ class InstallControllerHttpWelcome extends InstallControllerHttp
 	 */
 	public function display()
 	{
+		$this->can_upgrade = false;
+		if (file_exists(_PS_ROOT_DIR_.'/config/settings.inc.php'))
+		{
+			@include_once(_PS_ROOT_DIR_.'/config/settings.inc.php');
+			if (version_compare(_PS_VERSION_, _PS_INSTALL_VERSION_, '<'))
+			{
+				$this->can_upgrade = true;
+				$this->ps_version = _PS_VERSION_;
+			}
+		}
+
 		$this->displayTemplate('welcome');
 	}
 }
diff --git a/install-dev/langs/en/install.php b/install-dev/langs/en/install.php
index 082c26f8a..df7c015bb 100644
--- a/install-dev/langs/en/install.php
+++ b/install-dev/langs/en/install.php
@@ -3,6 +3,7 @@ return array(
 	'informations' => array(
 		'phone' => '+1 (888) 947-6543',
 		'documentation' => 'http://doc.prestashop.com/display/PS14/English+documentation',
+		'documentation_upgrade' => 'http://docs.prestashop.com/display/PS15/Updating+PrestaShop',
 		'forum' => 'http://www.prestashop.com/forums/',
 		'blog' => 'http://www.prestashop.com/blog/',
 		'support' => 'http://support.prestashop.com/en/',
diff --git a/install-dev/theme/views/welcome.phtml b/install-dev/theme/views/welcome.phtml
index 4e5b06a94..f5c21ef2c 100644
--- a/install-dev/theme/views/welcome.phtml
+++ b/install-dev/theme/views/welcome.phtml
@@ -4,6 +4,10 @@
 	<div class="warnBlock"><?php echo $this->l('PrestaShop requires at least 16M of memory to run, please check the memory_limit directive in php.ini or contact your host provider'); ?></div>
 <?php endif; ?>
 
+<?php if ($this->can_upgrade): ?>
+	<div class="warnBlock"><?php echo $this->l('You already have PrestaShop version %1$s installed. If you want to upgrade to the latest version please read our documentation : <a href="%2$s">%2$s</a>', $this->ps_version, $this->getDocumentationUpgradeLink()) ?></div>
+<?php endif; ?>
+
 <h2><?php echo $this->l('Welcome to the PrestaShop %s Installer.', _PS_INSTALL_VERSION_) ?></h2>
 <p><?php echo $this->l('The installation process should take only few minutes!') ?></p>
 <p><?php echo $this->l('If you need help, do not hesitate to check <a href="%1$s" target="_blank">our documentation</a> or to contact our support team: %2$s', $this->getDocumentationLink(), $this->getPhone()) ?></p>
@@ -15,7 +19,7 @@
 	<?php foreach ($this->language->getIsoList() as $iso): ?>
 		<li>
 			<label>
-				<input type="radio" value="<?php echo $iso ?>" <?php echo ($iso == $this->language->getLanguageIso()) ? "checked=\"checked\"" : '' ?> name="language" style="vertical-align: middle; margin-right: 0;" />
+				<input type="radio" value="<?php echo $iso ?>" <?php echo ($iso == $this->language->getLanguageIso()) ? 'checked="checked"' : '' ?> name="language" style="vertical-align: middle; margin-right: 0;" />
 				<?php if (file_exists(_PS_INSTALL_LANGS_PATH_.$iso.'/flag.jpg')): ?>
 					<img src="langs/<?php echo $iso ?>/flag.jpg" alt="<?php echo $iso ?>" style="vertical-align: middle;" />
 				<?php else: ?>