I've just started a new project in Umbraco version 7.5.8. I've created document types and am about to start writing markup in views by I am getting the strangest error.

The code below runs without an error. Just as one might expect:

@inherits Umbraco.Web.Mvc.UmbracoTemplatePage<ContentModels.Home2>
@using ContentModels = Umbraco.Web.PublishedContentModels;
@{
    Layout = null;
    var sth = 1;
}
<a href="">@sth</a>

The same code but with @sth in href attribute causes an error:

@inherits Umbraco.Web.Mvc.UmbracoTemplatePage<ContentModels.Home2>
@using ContentModels = Umbraco.Web.PublishedContentModels;
@{
    Layout = null;
    var sth = 1;
}
<a href="@sth">@sth</a>

The type name 'Object' does not exist in the type 'Umbraco.Web.PublishedContentModels.System

The error happens if razor is in class or href attribute but not when it is in data attribute...

This doesn't seem like an Umbraco error but at the same time this is a pretty simple piece of markup. Any ideas?