DOTNET_REFERENCE_ASSEMBLIES_PATH required when building on OS X?

I downloaded the .net core bits tonight and got it installed on OS X 10.11. I then cloned down a .Net Core project I had created and been working on from within Visual Studio 2015. When I run dotnet build it fails with the error below.

Johnathons-MacBook-Pro:Lightmap.Core johnathonsullinger$ dotnet build
Compiling Lightmap.Core for .NETFramework,Version=v4.5.1
/Users/johnathonsullinger/Source/GitHub/Scionwest/Lightmap/Source/Lightmap/Lightmap.Core/project.json(10,15): error DOTNET1012: The reference assemblies directory was not specified. You can set the location using the DOTNET_REFERENCE_ASSEMBLIES_PATH environment variable.

Compilation failed.
    0 Warning(s)
    1 Error(s)

Time elapsed 00:00:00.0201664

It looks like it’s related to the 4.5.1 framework; am I wrong in assuming that dotnet build knows that it can compile the dotnet5.4 framework and ignore the 4.5.1 framework?

This is my project.json

{
    "version": "1.0.0-*",
    "description": "Lightmap.Core Class Library",
    "authors": [ "johna" ],
    "tags": [ "" ],
    "projectUrl": "",
    "licenseUrl": "",

    "frameworks": {
        "net451": { },
        "dotnet5.4": {
        "dependencies": {
            "Microsoft.CSharp": "4.0.1-beta-23516",
            "System.Collections": "4.0.11-beta-23516",
            "System.Linq": "4.0.1-beta-23516",
            "System.Runtime": "4.0.21-beta-23516",
            "System.Threading": "4.0.11-beta-23516"
        }
        }
    }
    }

This can be reproduced by cloning my project and running dotnet build within the Lightmap.Core directory.

Is there a path I am supposed to add to my bash_profile, and if so what goes into that path?

[the404]

you juest remove net451 from frameworks section in package.json and dotnet build ,and dotnet run or publish,then it will be ok.

[scionwest]

@davidfowl yeah OS X, thanks! I’ll get those installed.

It would be awesome if you guys do end up shipping reference assemblies as packages. I’d like to remove my dependency on Mono altogether. They do a lot of good work but lag behind to much.