diff --git a/build/Targets/VSL.Imports.targets b/build/Targets/VSL.Imports.targets
index 53e4f96fc5d4a05d3f431c9d5d9addea885b3bd9..40ee4a056d99900eeb4f0613e46715ae439384f3 100644
--- a/build/Targets/VSL.Imports.targets
+++ b/build/Targets/VSL.Imports.targets
@@ -49,30 +49,6 @@
     </When>
   </Choose>
 
-  <!-- Work around mono + msbuild bug https://github.com/Microsoft/msbuild/issues/191 -->
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == 'DNXCore' and '$(OS)' != 'Windows_NT'">
-      <!-- Manually set assembly search paths so they don't get mangled later -->
-      <AssemblySearchPaths Condition=" '$(AssemblySearchPaths)' == ''">
-          {RawFileName};
-          $(OutDir)
-      </AssemblySearchPaths>
-      <RemoveAssemblyFoldersIfNoTargetFramework>false</RemoveAssemblyFoldersIfNoTargetFramework>
-  </PropertyGroup>
-
-  <!-- Work around issue in dotnet/roslyn issue #5213
-       Since MSBuild wants a reference assembly location and DNXCore doesn't have one,
-       trick MSBuild into using the .NETPortable,v5.0 reference assembly path which happens
-       to have the same set of reference assemblies as DNXCore (i.e., none). -->
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == 'DNXCore'">
-    <_TargetFrameworkDirectories>$([System.String]::Join(";", $([Microsoft.Build.Utilities.ToolLocationHelper]::GetPathToReferenceAssemblies(".NETPortable", "v5.0", ""))))</_TargetFrameworkDirectories>
-    <_FullFrameworkReferenceAssemblyPaths>$(_TargetFrameworkDirectories)</_FullFrameworkReferenceAssemblyPaths>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == 'DNXCore'">
-      <BaseNuGetRuntimeIdentifier Condition="'$(OS)' == 'Windows_NT'">win7</BaseNuGetRuntimeIdentifier>
-      <BaseNuGetRuntimeIdentifier Condition="'$(OS)' == 'Unix'">ubuntu.14.04</BaseNuGetRuntimeIdentifier>
-  </PropertyGroup>
-
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.VisualBasic.targets"
           Condition="'$(ProjectLanguage)' == 'VB' And '$(TargetFrameworkIdentifier)' == '.NETPortable'"/>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets"
@@ -89,6 +65,15 @@
   <Import Project="$(MSBuildExtensionsPath)\Microsoft\NuGet\Microsoft.NuGet.targets"
           Condition="'$(OS)' != 'Windows_NT'" />
 
+  <PropertyGroup Condition="
+      '$(TargetFrameworkIdentifier)' == '.NETPortable' AND
+      '$(TargetFrameworkVersion)' == 'v5.0' AND
+      '$(OutputType)' == 'Exe'">
+    <NuGetTargetMoniker>DNXCore,Version=v5.0</NuGetTargetMoniker>
+    <BaseNuGetRuntimeIdentifier Condition="'$(OS)' == 'Windows_NT'">win7</BaseNuGetRuntimeIdentifier>
+    <BaseNuGetRuntimeIdentifier Condition="'$(OS)' == 'Unix'">ubuntu.14.04</BaseNuGetRuntimeIdentifier>
+  </PropertyGroup>
+
   <!-- It looks like MSBuild has a bug on *nix where they aggressively
        directory separators from '\' to '/', even when the '\'
        is being used as an escape character in a define constant in VB.
diff --git a/cibuild.sh b/cibuild.sh
index 90b2ac8d1ba21cdb36a388a3a8d5fabe3fcb32cc..a663346db978529838c1edab2e3c196f346e61d2 100755
--- a/cibuild.sh
+++ b/cibuild.sh
@@ -205,9 +205,9 @@ set_mono_path()
     fi
 
     if [ "$OS_NAME" = "Darwin" ]; then
-        MONO_TOOLSET_NAME=mono.mac.3
+        MONO_TOOLSET_NAME=mono.mac.4
     elif [ "$OS_NAME" = "Linux" ]; then
-        MONO_TOOLSET_NAME=mono.linux.3
+        MONO_TOOLSET_NAME=mono.linux.4
     else
         echo "Error: Unsupported OS $OS_NAME"
         exit 1
diff --git a/src/Compilers/CSharp/CscCore/CscCore.csproj b/src/Compilers/CSharp/CscCore/CscCore.csproj
index f0b251a2a138a81f64d65aead05198c92c181186..ff2cdec1f8653a66b409713f99a919eae776e396 100644
--- a/src/Compilers/CSharp/CscCore/CscCore.csproj
+++ b/src/Compilers/CSharp/CscCore/CscCore.csproj
@@ -18,8 +18,10 @@
     <OutDir>$(OutDir)core-clr\</OutDir>
     <RestorePackages>true</RestorePackages>
     <AutoGenerateBindingRedirects>True</AutoGenerateBindingRedirects>
-    <TargetFrameworkIdentifier>DNXCore</TargetFrameworkIdentifier>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <TargetFrameworkIdentifier>.NETPortable</TargetFrameworkIdentifier>
     <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
+
     <!-- Misspelling, bug in NuGet targets -->
     <RuntimeIndentifier>x64</RuntimeIndentifier>
     <NuGetRuntimeIdentifier>$(BaseNuGetRuntimeIdentifier)-$(RuntimeIndentifier)</NuGetRuntimeIdentifier>
diff --git a/src/Compilers/VisualBasic/VbcCore/VbcCore.csproj b/src/Compilers/VisualBasic/VbcCore/VbcCore.csproj
index 553d15b56da2baad75a2d25f416ab80f1c9e7252..2f0069f6c0f59bf19ff10300f39be5e27b82e4e7 100644
--- a/src/Compilers/VisualBasic/VbcCore/VbcCore.csproj
+++ b/src/Compilers/VisualBasic/VbcCore/VbcCore.csproj
@@ -18,7 +18,8 @@
     <OutDir>$(OutDir)core-clr\</OutDir>
     <RestorePackages>true</RestorePackages>
     <AutoGenerateBindingRedirects>True</AutoGenerateBindingRedirects>
-    <TargetFrameworkIdentifier>DNXCore</TargetFrameworkIdentifier>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <TargetFrameworkIdentifier>.NETPortable</TargetFrameworkIdentifier>
     <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
     <!-- Misspelling, bug in NuGet targets -->
     <RuntimeIndentifier>x64</RuntimeIndentifier>
diff --git a/src/Interactive/CsiCore/CsiCore.csproj b/src/Interactive/CsiCore/CsiCore.csproj
index d3a653c38124e86c3bb4b1bb5edfc59fdca9609e..407706510fdbef9b67b8bd10defea64d0c5f59ac 100644
--- a/src/Interactive/CsiCore/CsiCore.csproj
+++ b/src/Interactive/CsiCore/CsiCore.csproj
@@ -16,7 +16,8 @@
     <OutDir>$(OutDir)core-clr\</OutDir>
     <RestorePackages>true</RestorePackages>
     <AutoGenerateBindingRedirects>True</AutoGenerateBindingRedirects>
-    <TargetFrameworkIdentifier>DNXCore</TargetFrameworkIdentifier>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <TargetFrameworkIdentifier>.NETPortable</TargetFrameworkIdentifier>
     <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
     <NoStdLib>true</NoStdLib>
   </PropertyGroup>
@@ -54,4 +55,4 @@
   <ImportGroup Label="Targets">
     <Import Project="..\..\..\build\Targets\VSL.Imports.targets" />
   </ImportGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/src/Interactive/VbiCore/VbiCore.vbproj b/src/Interactive/VbiCore/VbiCore.vbproj
index de96b1172ac6de7fea97b7dd6cd6feec80f96fde..c06ae50453dd0c96ea2755866c6740741af530ac 100644
--- a/src/Interactive/VbiCore/VbiCore.vbproj
+++ b/src/Interactive/VbiCore/VbiCore.vbproj
@@ -18,7 +18,8 @@
     <OutDir>$(OutDir)core-clr\</OutDir>
     <RestorePackages>true</RestorePackages>
     <AutoGenerateBindingRedirects>True</AutoGenerateBindingRedirects>
-    <TargetFrameworkIdentifier>DNXCore</TargetFrameworkIdentifier>
+    <ProjectTypeGuids>{14182A97-F7F0-4C62-8B27-98AA8AE2109A};{F184B08F-C81C-45F6-A57F-5ABD9991F28F}</ProjectTypeGuids>
+    <TargetFrameworkIdentifier>.NETPortable</TargetFrameworkIdentifier>
     <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
     <NoStdLib>true</NoStdLib>
   </PropertyGroup>