ambiguous match when calling method via reflection

When I try to call JsonConvert.DeserialiseObject via reflection I get an AmbiguousMatchException despite me specifying the type of the parameter for the overload I want to call

MethodInfo method = typeof(JsonConvert).GetMethod("DeserializeObject", new[] { typeof(string) });

Not sure what other info I can supply so that it finds a unique match

any ideas?