diff --git a/lib/xmlrpc/create.rb b/lib/xmlrpc/create.rb
index 2d38a44b30f906..282ea63e534555 100644
--- a/lib/xmlrpc/create.rb
+++ b/lib/xmlrpc/create.rb
@@ -210,6 +210,9 @@ def conv2value(param)
         when Float
           @writer.tag("double", param.to_s)
 
+        when BigDecimal
+          @writer.tag("double", param.to_s("F"))
+
         when Struct
           h = param.members.collect do |key|
             value = param[key]