diff --git a/tests/Compilation/Projects/Configuration/Configuration.csproj b/tests/Compilation/Projects/Configuration/Configuration.csproj
index 01ba7aab..95fc4b4c 100644
--- a/tests/Compilation/Projects/Configuration/Configuration.csproj
+++ b/tests/Compilation/Projects/Configuration/Configuration.csproj
@@ -8,7 +8,7 @@
   <ItemGroup>
     <PackageReference Include="Lambdajection" Version="$(LambdajectionVersion)" />
     <PackageReference Include="Lambdajection.Encryption" Version="$(LambdajectionVersion)" />
-    <PackageReference Include="NSubstitute" Version="4.3.0" />
+    <PackageReference Include="NSubstitute" Version="5.1.0" />
   </ItemGroup>
 
 </Project>
\ No newline at end of file
diff --git a/tests/Compilation/Projects/IamPermissions/IamPermissions.csproj b/tests/Compilation/Projects/IamPermissions/IamPermissions.csproj
index d6d3ee60..782d58dc 100644
--- a/tests/Compilation/Projects/IamPermissions/IamPermissions.csproj
+++ b/tests/Compilation/Projects/IamPermissions/IamPermissions.csproj
@@ -7,7 +7,7 @@
 
   <ItemGroup>
     <PackageReference Include="AWSSDK.S3" Version="3.7.0" />
-    <PackageReference Include="NSubstitute" Version="4.2.2" />
+    <PackageReference Include="NSubstitute" Version="5.1.0" />
     <PackageReference Include="Lambdajection" Version="$(LambdajectionVersion)" />
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/tests/Compilation/Projects/Permissionless/Permissionless.csproj b/tests/Compilation/Projects/Permissionless/Permissionless.csproj
index c2120e4d..deb6513b 100644
--- a/tests/Compilation/Projects/Permissionless/Permissionless.csproj
+++ b/tests/Compilation/Projects/Permissionless/Permissionless.csproj
@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="NSubstitute" Version="4.2.2" />
+    <PackageReference Include="NSubstitute" Version="5.1.0" />
     <PackageReference Include="Lambdajection" Version="$(LambdajectionVersion)" />
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/tests/Tests.csproj b/tests/Tests.csproj
index 05d4b629..5bdd465b 100644
--- a/tests/Tests.csproj
+++ b/tests/Tests.csproj
@@ -18,7 +18,7 @@
     <PackageReference Include="FluentAssertions" Version="5.10.3" />
     <PackageReference Include="Microsoft.Build.Locator" Version="1.5.5" />
     <PackageReference Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="4.5.0" />
-    <PackageReference Include="NSubstitute" Version="4.2.2" />
+    <PackageReference Include="NSubstitute" Version="5.1.0" />
     <PackageReference Include="NuGet.Frameworks" Version="6.5.0" />
     <PackageReference Include="NuGet.Commands" Version="6.5.0" />
     <PackageReference Include="NuGet.ProjectModel" Version="6.5.0" />