diff --git a/CoreDistributedCache/NHibernate.Caches.CoreDistributedCache.Tests/NHibernate.Caches.CoreDistributedCache.Tests.csproj b/CoreDistributedCache/NHibernate.Caches.CoreDistributedCache.Tests/NHibernate.Caches.CoreDistributedCache.Tests.csproj
index 3d9e782..de4cab7 100644
--- a/CoreDistributedCache/NHibernate.Caches.CoreDistributedCache.Tests/NHibernate.Caches.CoreDistributedCache.Tests.csproj
+++ b/CoreDistributedCache/NHibernate.Caches.CoreDistributedCache.Tests/NHibernate.Caches.CoreDistributedCache.Tests.csproj
@@ -26,7 +26,7 @@
   <ItemGroup>
     <PackageReference Include="log4net" Version="2.0.17" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.2" />
-    <PackageReference Include="NSubstitute" Version="3.1.0" />
+    <PackageReference Include="NSubstitute" Version="5.1.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)'=='net8.0'">
diff --git a/NHibernate.Caches.Common.Tests/NHibernate.Caches.Common.Tests.csproj b/NHibernate.Caches.Common.Tests/NHibernate.Caches.Common.Tests.csproj
index 8f19fdb..2bc1660 100644
--- a/NHibernate.Caches.Common.Tests/NHibernate.Caches.Common.Tests.csproj
+++ b/NHibernate.Caches.Common.Tests/NHibernate.Caches.Common.Tests.csproj
@@ -19,7 +19,7 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="NHibernate" Version="5.2.0" />
-    <PackageReference Include="NSubstitute" Version="3.1.0" />
+    <PackageReference Include="NSubstitute" Version="5.1.0" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)'=='net8.0'">
     <PackageReference Include="NUnitLite" Version="3.14.0" />
diff --git a/StackExchangeRedis/NHibernate.Caches.StackExchangeRedis.Tests/NHibernate.Caches.StackExchangeRedis.Tests.csproj b/StackExchangeRedis/NHibernate.Caches.StackExchangeRedis.Tests/NHibernate.Caches.StackExchangeRedis.Tests.csproj
index 785f4f6..fa72999 100644
--- a/StackExchangeRedis/NHibernate.Caches.StackExchangeRedis.Tests/NHibernate.Caches.StackExchangeRedis.Tests.csproj
+++ b/StackExchangeRedis/NHibernate.Caches.StackExchangeRedis.Tests/NHibernate.Caches.StackExchangeRedis.Tests.csproj
@@ -22,7 +22,7 @@
     <PackageReference Include="log4net" Version="2.0.17" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.2" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
-    <PackageReference Include="NSubstitute" Version="3.1.0" />
+    <PackageReference Include="NSubstitute" Version="5.1.0" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)'=='net8.0'">
     <PackageReference Include="NUnitLite" Version="3.14.0" />