diff --git a/check.php b/check.php
index f2b040e..0f4bf3e 100644
--- a/check.php
+++ b/check.php
@@ -73,7 +73,7 @@ class Check {
     }
 }
 
-if (isset($_GET['name'], $_GET['table'])) {
+if (isset($_GET['name'], $_GET['table']) && is_string($_GET['name']) && is_string($_GET['table'])) {
     $check = new Check();
     $check->run($_GET['name'], $_GET['table']);
 }
diff --git a/history.php b/history.php
index ed7eb64..c760e27 100644
--- a/history.php
+++ b/history.php
@@ -58,7 +58,7 @@ class History {
 
 $page = new Page("history");
 
-isset($_GET['uuid']) or die("Missing arguments (uuid).");
+isset($_GET['uuid']) && is_string($_GET['uuid']) or die("Missing arguments (uuid).");
 
 $staffhistory = (isset($_GET['staffhistory']) && $_GET['staffhistory'] === "1");
 
diff --git a/info.php b/info.php
index 88e6932..468a423 100644
--- a/info.php
+++ b/info.php
@@ -114,7 +114,7 @@ if ((substr($_SERVER['SCRIPT_NAME'], -strlen("info.php"))) !== "info.php") {
     return;
 }
 
-isset($_GET['type'], $_GET['id']) or die("Missing arguments (type, id).");
+isset($_GET['type'], $_GET['id']) && is_string($_GET['type']) && is_string($_GET['id']) or die("Missing arguments (type, id).");
 
 $type = $_GET['type'];
 $id = $_GET['id'];