diff --git a/src/SheetStream.Analyzers/SheetStream.Analyzers.csproj b/src/SheetStream.Analyzers/SheetStream.Analyzers.csproj
index 4545293..27687fb 100644
--- a/src/SheetStream.Analyzers/SheetStream.Analyzers.csproj
+++ b/src/SheetStream.Analyzers/SheetStream.Analyzers.csproj
@@ -25,8 +25,8 @@
     <!-- 4.8.0 is the oldest compiler the analyzer supports (VS 2022 17.8 / .NET SDK 8.0). Newer compilers load
          analyzers built against older Microsoft.CodeAnalysis, so staying low maximises compatibility. PrivateAssets
          keeps the compiler assemblies out of any package that references this project. -->
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.9.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="5.9.0" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/SheetStream.Generators/SheetStream.Generators.csproj b/src/SheetStream.Generators/SheetStream.Generators.csproj
index 99e2143..aafd07c 100644
--- a/src/SheetStream.Generators/SheetStream.Generators.csproj
+++ b/src/SheetStream.Generators/SheetStream.Generators.csproj
@@ -24,8 +24,8 @@
   <ItemGroup>
     <!-- 4.8.0 is the compiler shipped with .NET 8 / VS 17.8: the oldest host the generator supports.
          Newer SDKs (including .NET 10) load it unchanged. PrivateAssets keeps it out of any consumer's graph. -->
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.9.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="5.9.0" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/tests/SheetStream.Analyzers.Tests/SheetStream.Analyzers.Tests.csproj b/tests/SheetStream.Analyzers.Tests/SheetStream.Analyzers.Tests.csproj
index f676f74..d165a39 100644
--- a/tests/SheetStream.Analyzers.Tests/SheetStream.Analyzers.Tests.csproj
+++ b/tests/SheetStream.Analyzers.Tests/SheetStream.Analyzers.Tests.csproj
@@ -12,13 +12,13 @@
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Analyzer.Testing" Version="1.1.4" />
     <!-- The testing package only states a 1.0.1 floor for Workspaces, which restores as a .NET Framework package
          (NU1701). Pinning the same compiler version the analyzer builds against keeps restore clean. -->
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.8.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="5.9.0" />
     <!-- Transitive dependency of the NuGet client used by the testing package; its default version has a known
          vulnerability (NU1903), so pull a patched one. Not used by the tests themselves. -->
-    <PackageReference Include="System.Security.Cryptography.Pkcs" Version="10.0.13" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="System.Security.Cryptography.Pkcs" Version="10.0.14" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.11.0" />
     <PackageReference Include="xunit" Version="2.9.3" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="4.0.1" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/tests/SheetStream.Generators.Tests/SheetStream.Generators.Tests.csproj b/tests/SheetStream.Generators.Tests/SheetStream.Generators.Tests.csproj
index 280a6c2..57ba31d 100644
--- a/tests/SheetStream.Generators.Tests/SheetStream.Generators.Tests.csproj
+++ b/tests/SheetStream.Generators.Tests/SheetStream.Generators.Tests.csproj
@@ -10,11 +10,11 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.11.0" />
     <PackageReference Include="xunit" Version="2.9.3" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="4.0.1" />
     <!-- Same Roslyn the generator is compiled against, for the CSharpGeneratorDriver tests. -->
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.9.0" />
   </ItemGroup>
 
   <ItemGroup>