diff --git a/src/Pipedrive.net.Tests/Pipedrive.Tests.csproj b/src/Pipedrive.net.Tests/Pipedrive.Tests.csproj
index 5ef3157..979cf61 100644
--- a/src/Pipedrive.net.Tests/Pipedrive.Tests.csproj
+++ b/src/Pipedrive.net.Tests/Pipedrive.Tests.csproj
@@ -8,7 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
-    <PackageReference Include="NSubstitute" Version="4.4.0" />
+    <PackageReference Include="NSubstitute" Version="5.1.0" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.1.118">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>