diff --git a/system/core/Input.php b/system/core/Input.php
index 8b34943..dacd7db 100644
--- a/system/core/Input.php
+++ b/system/core/Input.php
@@ -907,8 +907,8 @@ public function is_cli_request()
 	public function method($upper = FALSE)
 	{
 		return ($upper)
-			? strtoupper($this->server('REQUEST_METHOD'))
-			: strtolower($this->server('REQUEST_METHOD'));
+			? strtoupper((string) $this->server('REQUEST_METHOD'))
+			: strtolower((string) $this->server('REQUEST_METHOD'));
 	}
 
 	// ------------------------------------------------------------------------
diff --git a/system/core/Security.php b/system/core/Security.php
index a21bf07..3733da5 100644
--- a/system/core/Security.php
+++ b/system/core/Security.php
@@ -221,7 +221,7 @@ public function __construct()
 	public function csrf_verify()
 	{
 		// If it's not a POST request we will set the CSRF cookie
-		if (strtoupper($_SERVER['REQUEST_METHOD']) !== 'POST') {
+		if (strtoupper((string) $_SERVER['REQUEST_METHOD']) !== 'POST') {
 			return $this->csrf_set_cookie();
 		}