diff --git a/NetCoreTests/NetCoreTests.csproj b/NetCoreTests/NetCoreTests.csproj
index 1b192e1..275008e 100644
--- a/NetCoreTests/NetCoreTests.csproj
+++ b/NetCoreTests/NetCoreTests.csproj
@@ -9,6 +9,8 @@
     <PackageReference Include="MSTest.TestFramework" Version="2.2.8"/>
     <PackageReference Include="Microsoft.NET.Test.SDK" Version="17.1.0"/>
     <PackageReference Include="System.Net.Http" Version="4.3.4" />
+    <PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
+
     <ProjectReference Include="..\EPPlus\EPPlusSDK.csproj"/>
 
     <None Include="TestWorkbooks/**" CopyToOutputDirectory="PreserveNewest"/>