diff --git a/phpBB/common.php b/phpBB/common.php
index ea05515075..0630d48934 100644
--- a/phpBB/common.php
+++ b/phpBB/common.php
@@ -111,7 +111,33 @@ require($phpbb_root_path . 'config.' . $phpEx);
 
 if (!defined('PHPBB_INSTALLED'))
 {
-	header('Location: install/index.' . $phpEx);
+	// Redirect the user to the installer
+	// We have to generate a full HTTP/1.1 header here since we can't guarantee to have any of the information
+	// available as used by the redirect function
+	$server_name = (!empty($_SERVER['SERVER_NAME'])) ? $_SERVER['SERVER_NAME'] : getenv('SERVER_NAME');
+	$server_port = (!empty($_SERVER['SERVER_PORT'])) ? (int) $_SERVER['SERVER_PORT'] : (int) getenv('SERVER_PORT');
+	$secure = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on') ? 1 : 0;
+
+	$script_name = (!empty($_SERVER['PHP_SELF'])) ? $_SERVER['PHP_SELF'] : getenv('PHP_SELF');
+	if (!$script_name)
+	{
+		$script_name = (!empty($_SERVER['REQUEST_URI'])) ? $_SERVER['REQUEST_URI'] : getenv('REQUEST_URI');
+	}
+
+	// Replace backslashes and doubled slashes (could happen on some proxy setups)
+	$script_name = str_replace(array('\\', '//'), '/', $script_name);
+	$script_path = trim(dirname($script_name));
+	$script_path = rtrim($script_patch, '/');
+
+	$url = (($secure) ? 'https://' : 'http://') . $server_name;
+
+	if ($server_port && (($secure && $server_port <> 443) || (!$secure && $server_port <> 80)))
+	{
+		$url .= ':' . $server_port;
+	}
+
+	$url .= $script_path . '/install/index.' . $phpEx;
+	header('Location: ' . $url);
 	exit;
 }
 
diff --git a/phpBB/install/index.php b/phpBB/install/index.php
index 51ab82ba3c..d22545a56a 100755
--- a/phpBB/install/index.php
+++ b/phpBB/install/index.php
@@ -372,6 +372,39 @@ class module
 		return (isset($lang[$this->module->page_title])) ? $lang[$this->module->page_title] : $this->module->page_title;
 	}
 
+	/**
+	* Generate an HTTP/1.1 header to redirect the user to another page
+	* This is used during the installation when we do not have a database available to call the normal redirect function
+	* @param string $page The page to redirect to relative to the installer root path
+	*/
+	function redirect($page)
+	{
+		$server_name = (!empty($_SERVER['SERVER_NAME'])) ? $_SERVER['SERVER_NAME'] : getenv('SERVER_NAME');
+		$server_port = (!empty($_SERVER['SERVER_PORT'])) ? (int) $_SERVER['SERVER_PORT'] : (int) getenv('SERVER_PORT');
+		$secure = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on') ? 1 : 0;
+
+		$script_name = (!empty($_SERVER['PHP_SELF'])) ? $_SERVER['PHP_SELF'] : getenv('PHP_SELF');
+		if (!$script_name)
+		{
+			$script_name = (!empty($_SERVER['REQUEST_URI'])) ? $_SERVER['REQUEST_URI'] : getenv('REQUEST_URI');
+		}
+
+		// Replace backslashes and doubled slashes (could happen on some proxy setups)
+		$script_name = str_replace(array('\\', '//'), '/', $script_name);
+		$script_path = trim(dirname($script_name));
+
+		$url = (($secure) ? 'https://' : 'http://') . $server_name;
+
+		if ($server_port && (($secure && $server_port <> 443) || (!$secure && $server_port <> 80)))
+		{
+			$url .= ':' . $server_port;
+		}
+
+		$url .= $script_path . '/' . $page;
+		header('Location: ' . $url);
+		exit;
+	}
+
 	/**
 	* Generate the navigation tabs
 	*/
diff --git a/phpBB/install/install_install.php b/phpBB/install/install_install.php
index 780301d547..9e0a3cc002 100755
--- a/phpBB/install/install_install.php
+++ b/phpBB/install/install_install.php
@@ -537,8 +537,7 @@ class install_install extends module
 		{
 			// Someone's been silly and tried calling this page direct
 			// So we send them back to the start to do it again properly
-			header('Location: index.' . $phpEx . '?mode=install');
-			exit;
+			$this->p_master->redirect("index?mode=install");
 		}
 
 		$s_hidden_fields = ($img_imagick) ? '<input type="hidden" name="img_imagick" value="' . addslashes($img_imagick) . '" />' : '';
@@ -696,8 +695,7 @@ class install_install extends module
 		{
 			// Someone's been silly and tried calling this page direct
 			// So we send them back to the start to do it again properly
-			header('Location: index.' . $phpEx . '?mode=install');
-			exit;
+			$this->p_master->redirect("index?mode=install");
 		}
 
 		$s_hidden_fields = ($img_imagick) ? '<input type="hidden" name="img_imagick" value="' . addslashes($img_imagick) . '" />' : '';
@@ -841,8 +839,7 @@ class install_install extends module
 		{
 			// Someone's been silly and tried calling this page direct
 			// So we send them back to the start to do it again properly
-			header('Location: index.' . $phpEx . '?mode=install');
-			exit;
+			$this->p_master->redirect("index?mode=install");
 		}
 
 		$s_hidden_fields = ($img_imagick) ? '<input type="hidden" name="img_imagick" value="' . addslashes($img_imagick) . '" />' : '';
@@ -925,8 +922,7 @@ class install_install extends module
 		{
 			// Someone's been silly and tried calling this page direct
 			// So we send them back to the start to do it again properly
-			header('Location: index.' . $phpEx . '?mode=install');
-			exit;
+			$this->p_master->redirect("index?mode=install");
 		}
 
 		$cookie_domain = ($server_name != '') ? $server_name : (!empty($_SERVER['SERVER_NAME'])) ? $_SERVER['SERVER_NAME'] : getenv('SERVER_NAME');