diff --git a/webui/src/main/java/com/muwire/webui/InitServlet.java b/webui/src/main/java/com/muwire/webui/InitServlet.java
index 6b079981..adc10eb7 100644
--- a/webui/src/main/java/com/muwire/webui/InitServlet.java
+++ b/webui/src/main/java/com/muwire/webui/InitServlet.java
@@ -8,6 +8,9 @@ import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import com.muwire.core.Constants;
+import com.muwire.core.util.DataUtil;
+
 public class InitServlet extends HttpServlet {
 
     @Override
@@ -17,6 +20,9 @@ public class InitServlet extends HttpServlet {
             if (nickname == null || nickname.trim().length() == 0)
                 throw new Exception("Nickname cannot be blank");
             
+            if (!DataUtil.isValidName(nickname))
+                throw new Exception("Nickname cannot contain any of " + Constants.INVALID_NICKNAME_CHARS);
+            
             String downloadLocation = req.getParameter("download_location");
             if (downloadLocation == null)
                 throw new Exception("Download location cannot be blank");