diff --git a/app/controllers/webhooks_controller.rb b/app/controllers/webhooks_controller.rb
index 7271ac5f6b8..74024b31524 100644
--- a/app/controllers/webhooks_controller.rb
+++ b/app/controllers/webhooks_controller.rb
@@ -49,7 +49,7 @@ class WebhooksController < ActionController::Base
   end
 
   def mandrill
-    events = params["mandrill_events"]
+    events = JSON.parse(params["mandrill_events"])
     events.each do |event|
       message_id = event.dig("msg", "metadata", "message_id")
       to_address = event.dig("msg", "email")
diff --git a/spec/requests/webhooks_controller_spec.rb b/spec/requests/webhooks_controller_spec.rb
index 070c8039924..53b5f062565 100644
--- a/spec/requests/webhooks_controller_spec.rb
+++ b/spec/requests/webhooks_controller_spec.rb
@@ -142,7 +142,7 @@ RSpec.describe WebhooksController do
               "message_id" => message_id
             }
           }
-        }]
+        }].to_json
       }
 
       expect(response.status).to eq(200)