diff --git a/ClosedXML_Examples/ClosedXML_Examples.csproj b/ClosedXML_Examples/ClosedXML_Examples.csproj
index b7d0223..7971679 100644
--- a/ClosedXML_Examples/ClosedXML_Examples.csproj
+++ b/ClosedXML_Examples/ClosedXML_Examples.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.0;net452;net461</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net452;net461</TargetFrameworks>
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard1.6' ">
diff --git a/ClosedXML_Sandbox/ClosedXML_Sandbox.csproj b/ClosedXML_Sandbox/ClosedXML_Sandbox.csproj
index 35397d6..1582c1d 100644
--- a/ClosedXML_Sandbox/ClosedXML_Sandbox.csproj
+++ b/ClosedXML_Sandbox/ClosedXML_Sandbox.csproj
@@ -2,12 +2,35 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFrameworks>netcoreapp2.0;net452;net461</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;net452;net461</TargetFrameworks>
   </PropertyGroup>
 
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
+    <DefineConstants>$(DefineConstants);_NETSTANDARD_;_NETSTANDARD2_0_</DefineConstants>
+  </PropertyGroup>
+
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'net452' ">
+    <DefineConstants>$(DefineConstants);_NETFRAMEWORK_;_NET452_</DefineConstants>
+  </PropertyGroup>
+
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'net461' ">
+    <DefineConstants>$(DefineConstants);_NETFRAMEWORK_;_NET461_</DefineConstants>
+  </PropertyGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
+    <PackageReference Include="System.ComponentModel.Annotations" Version="4.4.0" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'net452'">
+    <Reference Include="System.ComponentModel.DataAnnotations" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'net461'">
+    <Reference Include="System.ComponentModel.DataAnnotations" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\ClosedXML\ClosedXML.csproj" />
-    <Reference Include="System.ComponentModel.DataAnnotations" />
   </ItemGroup>
 
 </Project>
diff --git a/ClosedXML_Tests/ClosedXML_Tests.csproj b/ClosedXML_Tests/ClosedXML_Tests.csproj
index efe9be7..6f90c25 100644
--- a/ClosedXML_Tests/ClosedXML_Tests.csproj
+++ b/ClosedXML_Tests/ClosedXML_Tests.csproj
@@ -14,7 +14,7 @@
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.0' ">
-    <DefineConstants>$(DefineConstants);_NETSTANDARD_;_NETSTANDARD2_0_</DefineConstants>
+    <DefineConstants>$(DefineConstants);_NETSTANDARD_;_netcoreapp2_0_</DefineConstants>
   </PropertyGroup>
 
   <PropertyGroup Condition=" '$(TargetFramework)' == 'net452' ">
diff --git a/ClosedXML_Tests/OleDb/OleDbTests.cs b/ClosedXML_Tests/OleDb/OleDbTests.cs
index a687b35..48f1855 100644
--- a/ClosedXML_Tests/OleDb/OleDbTests.cs
+++ b/ClosedXML_Tests/OleDb/OleDbTests.cs
@@ -1,4 +1,5 @@
-using ClosedXML.Excel;
+#if !APPVEYOR && _NETFRAMEWORK_
+using ClosedXML.Excel;
 using NUnit.Framework;
 using System;
 using System.Collections.Generic;
@@ -12,7 +13,6 @@
     [TestFixture]
     public class OleDbTests
     {
-#if !APPVEYOR && _NETFRAMEWORK_
         [Test]
         public void TestOleDbValues()
         {
@@ -77,7 +77,6 @@
                 }
             }
         }
-#endif
 
         private string CreateTestFile()
         {
@@ -144,3 +143,4 @@
         }
     }
 }
+#endif