diff --git a/spec/views/wsdl.builder b/spec/views/wsdl.builder
index 8938d0b..4ad36b2 100644
--- a/spec/views/wsdl.builder
+++ b/spec/views/wsdl.builder
@@ -12,7 +12,12 @@ xml.definitions 'xmlns' => 'http://schemas.xmlsoap.org/wsdl/',
     xml.tag! "schema", :targetNamespace => settings.namespace, :xmlns => 'http://www.w3.org/2001/XMLSchema' do
       defined = []
       wsdl.each do |operation, formats|
-        (formats[:in] + formats[:out]).each do |p|
+        formats[:in]||={}
+        formats[:out]||={}
+        formats[:in].each do |p|
+          wsdl_type xml, p, defined
+        end
+        formats[:out].each do |p|
           wsdl_type xml, p, defined
         end
       end
@@ -65,4 +70,4 @@ xml.definitions 'xmlns' => 'http://schemas.xmlsoap.org/wsdl/',
       end
     end
   end
-end
\ No newline at end of file
+end