HostingEnvironment does not contain a definition for IsHosted

I'm developing a C# application and I need to find out if I'm under IIS or not. I've seen some question on SO about using the HostingEnvironment.IsHosted method. Unfortunately if I write something like:

if (HostingEnvironment.IsHosted)
{
    // on IIS
}
else
{
   // not on IIS
}

I get a compile error:

HostingEnvironment does not contain a definition for IsHosted

I'm using: Microsoft.AspNetCore.Hosting; Microsoft.AspNetCore.Hosting.Internal;

EDIT

Tried using System.Web.Hosting.HostingEnvironment.IsHosted as suggested but it didn't work