diff --git a/src/Numerics/Numerics-2017.csproj b/src/Numerics/Numerics-2017.csproj
index 45933ab2..377e9e9b 100644
--- a/src/Numerics/Numerics-2017.csproj
+++ b/src/Numerics/Numerics-2017.csproj
@@ -15,7 +15,7 @@
         <AssemblyName>MathNet.Numerics</AssemblyName>
         <RootNamespace>MathNet.Numerics</RootNamespace>
     </PropertyGroup>
-    <ItemGroup>
+    <ItemGroup Condition="'$(TargetFramework)' == 'net40'">
         <Reference Include="System" />
         <Reference Include="System.Core" />
         <Reference Include="System.Numerics" />