diff --git a/src/org/opencms/flex/CmsFlexResponse.java b/src/org/opencms/flex/CmsFlexResponse.java
index 55c41f35be8..53ea6f6be85 100644
--- a/src/org/opencms/flex/CmsFlexResponse.java
+++ b/src/org/opencms/flex/CmsFlexResponse.java
@@ -435,6 +435,11 @@ public void addCookie(Cookie cookie) {
             header.append("; Secure");
         }
 
+        // HttpOnly
+        if (cookie.isHttpOnly()) {
+            header.append("; HttpOnly");
+        }
+
         addHeader("Set-Cookie", header.toString());
     }