diff --git a/Ocaramba.Tests.NUnit/Ocaramba.Tests.NUnit.csproj b/Ocaramba.Tests.NUnit/Ocaramba.Tests.NUnit.csproj
index 5f004783..49ac7c8f 100644
--- a/Ocaramba.Tests.NUnit/Ocaramba.Tests.NUnit.csproj
+++ b/Ocaramba.Tests.NUnit/Ocaramba.Tests.NUnit.csproj
@@ -10,7 +10,7 @@
     <PackageReference Include="Microsoft.TestPlatform.TestHost" Version="17.4.0" />
     <PackageReference Include="NLog" Version="5.1.1" />
     
-    <PackageReference Include="NPOI" Version="2.6.0" />
+    <PackageReference Include="NPOI" Version="2.5.6" />
     <PackageReference Include="NUnit" Version="3.13.3" />
     <PackageReference Include="NUnit.Runners" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.3.1">