diff --git a/app/code/local/MagePal/GoogleTagManager/Block/Tm.php b/app/code/local/MagePal/GoogleTagManager/Block/Tm.php
index edf5a55..17a56c5 100755
--- a/app/code/local/MagePal/GoogleTagManager/Block/Tm.php
+++ b/app/code/local/MagePal/GoogleTagManager/Block/Tm.php
@@ -81,7 +81,7 @@ protected function getOrdersTrackingCode()
             );
 
 
-            $result[] = sprintf("dataLayer.push(%s);", json_encode($transaction));
+            $result[] = sprintf("dataLayer.push(%s);", json_encode($transaction, JSON_NUMERIC_CHECK));
         }
 
         return implode("\n", $result) . "\n";