diff --git a/tests/SimpleAccounting.UnitTests/SimpleAccounting.UnitTests.csproj b/tests/SimpleAccounting.UnitTests/SimpleAccounting.UnitTests.csproj
index 4f9df4b..fe33a1d 100644
--- a/tests/SimpleAccounting.UnitTests/SimpleAccounting.UnitTests.csproj
+++ b/tests/SimpleAccounting.UnitTests/SimpleAccounting.UnitTests.csproj
@@ -15,7 +15,7 @@
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-    <PackageReference Include="NSubstitute" Version="5.3.0" />
+    <PackageReference Include="NSubstitute" Version="6.0.0" />
     <!-- license is apache 2.0 -->
     <PackageReference Include="xunit.v3" Version="3.2.2"/>
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5">