diff --git a/server/src/main/java/ctbrec/recorder/server/RecorderServlet.java b/server/src/main/java/ctbrec/recorder/server/RecorderServlet.java
index 8e49a4d4..b4cedc9e 100644
--- a/server/src/main/java/ctbrec/recorder/server/RecorderServlet.java
+++ b/server/src/main/java/ctbrec/recorder/server/RecorderServlet.java
@@ -271,6 +271,9 @@ public class RecorderServlet extends AbstractCtbrecServlet {
 
     private void startByName(Request request) throws InvalidKeyException, NoSuchAlgorithmException, IOException {
         String[] input = request.model.getUrl().split(":");
+        if (input.length != 2) {
+            throw new IllegalArgumentException("Invalid input. Should be site:model");
+        }
         String siteName = input[0];
         String modelName = input[1];
         for (Site site : sites) {