diff --git a/static/js/copyvios.js b/static/js/copyvios.js
index 901e486..47d18d8 100644
--- a/static/js/copyvios.js
+++ b/static/js/copyvios.js
@@ -16,7 +16,7 @@ function get_cookie(name) {
 }
 
 function set_cookie(name, value, days) {
-    value = window.btoa(value);
+    value = window.btoa("--ets1" + value);
     var path = window.location.pathname.split("/", 2)[1];
     if (days) {
         var date = new Date();
diff --git a/toolserver/cookies.py b/toolserver/cookies.py
index 4362533..1d1d6f6 100644
--- a/toolserver/cookies.py
+++ b/toolserver/cookies.py
@@ -6,6 +6,8 @@ from datetime import datetime, timedelta
 from os import path
 
 class _CookieManager(SimpleCookie):
+    MAGIC = "--ets1"
+
     def __init__(self, environ):
         self._path = path.split(environ["PATH_INFO"])[0]
         try:
@@ -19,12 +21,15 @@ class _CookieManager(SimpleCookie):
     def value_decode(self, value):
         unquoted = super(_CookieManager, self).value_decode(value)[0]
         try:
-            return base64.b64decode(unquoted).decode("utf8"), value
+            decoded = base64.b64decode(unquoted).decode("utf8")
         except (TypeError, UnicodeDecodeError):
             return False, "False"
+        if decoded.startswith(self.MAGIC):
+            return decoded[len(self.MAGIC):], value
+        return False, "False"
 
     def value_encode(self, value):
-        encoded = base64.b64encode(value.encode("utf8"))
+        encoded = base64.b64encode(self.MAGIC + value.encode("utf8"))
         quoted = super(_CookieManager, self).value_encode(encoded)[1]
         return value, quoted
 
@@ -45,4 +50,4 @@ def set_cookie(headers, cookies, key, value, days=0):
     headers.append(("Set-Cookie", cookies[key].OutputString()))
 
 def delete_cookie(headers, cookies, key):
-    set_cookie(headers, cookies, key, "", days=-1)
+    set_cookie(headers, cookies, key, u"", days=-1)
diff --git a/toolserver/settings.py b/toolserver/settings.py
index cc42ab8..f3609e5 100644
--- a/toolserver/settings.py
+++ b/toolserver/settings.py
@@ -22,8 +22,7 @@ def main(context, environ, headers):
             delete_cookie(headers, cookies, query.cookie)
         elif query.all:
             for cookie in cookies.values():
-                if cookie.path.startswith(cookies.path):
-                    delete_cookie(headers, cookies, cookie.key)
+                delete_cookie(headers, cookies, cookie.key)
 
     bot = get_bot()
     langs, projects = get_sites(bot)