diff --git a/src/code/Cache/Block/Messages.php b/src/code/Cache/Block/Messages.php
index 7e61778..5b207d6 100644
--- a/src/code/Cache/Block/Messages.php
+++ b/src/code/Cache/Block/Messages.php
@@ -11,12 +11,16 @@ class Made_Cache_Block_Messages extends Mage_Core_Block_Messages
 {
     protected function _toHtml()
     {
-        if (Mage::helper('cache/varnish')->shouldUse()
-                && !$this->getBypassVarnish()) {
+        $helper = Mage::helper('cache/varnish');
+        $request = Mage::app()->getRequest();
+        if ($helper->shouldUse()
+            && $helper->getRequestTtl($request)
+            && !$this->getBypassVarnish()
+        ) {
             return Mage::helper('cache/varnish')
                     ->getEsiTag('madecache/varnish/messages');
         }
 
         return parent::_toHtml();
     }
-}
\ No newline at end of file
+}
diff --git a/src/code/Cache/Model/VarnishObserver.php b/src/code/Cache/Model/VarnishObserver.php
index daf0148..df69820 100644
--- a/src/code/Cache/Model/VarnishObserver.php
+++ b/src/code/Cache/Model/VarnishObserver.php
@@ -60,6 +60,11 @@ public function addLayoutHandle(Varien_Event_Observer $observer)
         if (!Mage::helper('cache/varnish')->shouldUse()) {
             return;
         }
+        $request = Mage::app()->getRequest();
+
+        if (!Mage::helper('cache/varnish')->getRequestTtl($request)) {
+            return;
+        }
 
         $observer->getEvent()
             ->getLayout()
@@ -77,6 +82,14 @@ public function addEsiTag(Varien_Event_Observer $observer)
         if (!Mage::helper('cache/varnish')->shouldUse()) {
             return;
         }
+        $headers = Mage::app()->getResponse()->getHeaders();
+        foreach ($headers as $header) {
+            if (strtolower($header['name']) == 'content-type') {
+                if ($header['value'] == 'application/json') {
+                    return;
+                }
+            }
+        }
 
         $block = $observer->getEvent()->getBlock();