diff --git a/templates/csharp/tests/CustomerApi.Tests/CustomerApi.Tests.csproj b/templates/csharp/tests/CustomerApi.Tests/CustomerApi.Tests.csproj
index 17473a7..590e0ea 100644
--- a/templates/csharp/tests/CustomerApi.Tests/CustomerApi.Tests.csproj
+++ b/templates/csharp/tests/CustomerApi.Tests/CustomerApi.Tests.csproj
@@ -7,7 +7,7 @@
     <PackageReference Include="FluentAssertions" Version="7.0.0" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
-    <PackageReference Include="NSubstitute" Version="5.3.0" />
+    <PackageReference Include="NSubstitute" Version="6.0.0" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
diff --git a/templates/csharp/tests/CustomerApi.Tests/packages.lock.json b/templates/csharp/tests/CustomerApi.Tests/packages.lock.json
index a69ec4c..76e854b 100644
--- a/templates/csharp/tests/CustomerApi.Tests/packages.lock.json
+++ b/templates/csharp/tests/CustomerApi.Tests/packages.lock.json
@@ -40,9 +40,9 @@
       },
       "NSubstitute": {
         "type": "Direct",
-        "requested": "[5.3.0, )",
-        "resolved": "5.3.0",
-        "contentHash": "lJ47Cps5Qzr86N99lcwd+OUvQma7+fBgr8+Mn+aOC0WrlqMNkdivaYD9IvnZ5Mqo6Ky3LS7ZI+tUq1/s9ERd0Q==",
+        "requested": "[6.0.0, )",
+        "resolved": "6.0.0",
+        "contentHash": "0gvKMbiJ+/WrfbcfBfqRZZrvfLJcd3rqkqVMjjlY5dtmLRVzMY+o/K/rJUStofQ2haSr9Vd04YDfvZtVVGS3/A==",
         "dependencies": {
           "Castle.Core": "5.1.1"
         }