diff --git a/lib/active_merchant/billing/gateways/secure_pay_au.rb b/lib/active_merchant/billing/gateways/secure_pay_au.rb
index 13f37c96254..a23c6f65967 100644
--- a/lib/active_merchant/billing/gateways/secure_pay_au.rb
+++ b/lib/active_merchant/billing/gateways/secure_pay_au.rb
@@ -181,7 +181,7 @@ def build_request(action, body)
       end
 
       def commit(action, request)
-        response = parse(ssl_post(test? ? self.test_url : self.live_url, build_request(action, request)))
+        response = parse(ssl_post(test? ? self.test_url : self.live_url, build_request(action, request), {"Content-Type" => "text/xml; charset=utf-8"}))
 
         Response.new(
           success?(response),
@@ -241,7 +241,7 @@ def build_periodic_request(body)
 
       def commit_periodic(request)
         my_request = build_periodic_request(request)
-        response = parse(ssl_post(test? ? self.test_periodic_url : self.live_periodic_url, my_request))
+        response = parse(ssl_post(test? ? self.test_periodic_url : self.live_periodic_url, my_request, {"Content-Type" => "text/xml; charset=utf-8"}))
 
         Response.new(
           success?(response),