diff --git a/Directory.Build.props b/Directory.Build.props
index d225d952..54aab334 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -6,4 +6,12 @@
 		<PublicKey>0024000004800000940000000602000000240000525341310004000001000100917b2e28a0dcd1de99a208f70383c300caa03729b1f9cdad97cb11a127f822aa36aad08225cc24312de1fadf3aeafc7ab6c2c4b588d5e88c2b61f0a56e02df1b6aa11d0c3e4ee6675f24b20dbd75ee4fc229f82b0eeeafe1a5bc376d5e5f9a5c4320267921d9a962cc5f58ccc94e7127db3119bafedfb76fd3a7b1f2d22155ac</PublicKey>
 	</PropertyGroup>
 
+	<PropertyGroup>
+		<!-- The oldest Roslyn the generator and analyzers must load in. A compiler host older than this
+		refuses to load them (CS9057), so IntelliSense silently loses all generated members. Cannot go below
+		5.0: the emitted `Mock.g.cs` declares `CreateMock` in a C# 14 extension block. The generator tests
+		pin the same version so a newer API creeping in fails the build instead of the users' IDE. -->
+		<MinimumRoslynVersion>5.0.0</MinimumRoslynVersion>
+	</PropertyGroup>
+
 </Project>
diff --git a/Source/Mockolate.Analyzers.CodeFixers/Mockolate.Analyzers.CodeFixers.csproj b/Source/Mockolate.Analyzers.CodeFixers/Mockolate.Analyzers.CodeFixers.csproj
index c2691888..d69dcce9 100644
--- a/Source/Mockolate.Analyzers.CodeFixers/Mockolate.Analyzers.CodeFixers.csproj
+++ b/Source/Mockolate.Analyzers.CodeFixers/Mockolate.Analyzers.CodeFixers.csproj
@@ -18,9 +18,9 @@
 			<PrivateAssets>all</PrivateAssets>
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 		</PackageReference>
-		<PackageReference Include="Microsoft.CodeAnalysis.Common"/>
-		<PackageReference Include="Microsoft.CodeAnalysis.CSharp"/>
-		<PackageReference Include="Microsoft.CodeAnalysis.Workspaces.Common"/>
+		<PackageReference Include="Microsoft.CodeAnalysis.Common" VersionOverride="$(MinimumRoslynVersion)"/>
+		<PackageReference Include="Microsoft.CodeAnalysis.CSharp" VersionOverride="$(MinimumRoslynVersion)"/>
+		<PackageReference Include="Microsoft.CodeAnalysis.Workspaces.Common" VersionOverride="$(MinimumRoslynVersion)"/>
 	</ItemGroup>
 
 	<ItemGroup>
diff --git a/Source/Mockolate.Analyzers/Mockolate.Analyzers.csproj b/Source/Mockolate.Analyzers/Mockolate.Analyzers.csproj
index afa73786..d8e761a2 100644
--- a/Source/Mockolate.Analyzers/Mockolate.Analyzers.csproj
+++ b/Source/Mockolate.Analyzers/Mockolate.Analyzers.csproj
@@ -22,8 +22,8 @@
 			<PrivateAssets>all</PrivateAssets>
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 		</PackageReference>
-		<PackageReference Include="Microsoft.CodeAnalysis.Common"/>
-		<PackageReference Include="Microsoft.CodeAnalysis.CSharp"/>
+		<PackageReference Include="Microsoft.CodeAnalysis.Common" VersionOverride="$(MinimumRoslynVersion)"/>
+		<PackageReference Include="Microsoft.CodeAnalysis.CSharp" VersionOverride="$(MinimumRoslynVersion)"/>
 	</ItemGroup>
 
 	<ItemGroup>
diff --git a/Source/Mockolate.SourceGenerators/Mockolate.SourceGenerators.csproj b/Source/Mockolate.SourceGenerators/Mockolate.SourceGenerators.csproj
index bf83e85a..bd2e20a4 100644
--- a/Source/Mockolate.SourceGenerators/Mockolate.SourceGenerators.csproj
+++ b/Source/Mockolate.SourceGenerators/Mockolate.SourceGenerators.csproj
@@ -17,7 +17,7 @@
 
 	<ItemGroup>
 		<PackageReference Include="Microsoft.CodeAnalysis.Analyzers" PrivateAssets="all"/>
-		<PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all"/>
+		<PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all" VersionOverride="$(MinimumRoslynVersion)"/>
 	</ItemGroup>
 
 	<ItemGroup>
diff --git a/Tests/Mockolate.SourceGenerators.Tests/Mockolate.SourceGenerators.Tests.csproj b/Tests/Mockolate.SourceGenerators.Tests/Mockolate.SourceGenerators.Tests.csproj
index ec287860..beca3921 100644
--- a/Tests/Mockolate.SourceGenerators.Tests/Mockolate.SourceGenerators.Tests.csproj
+++ b/Tests/Mockolate.SourceGenerators.Tests/Mockolate.SourceGenerators.Tests.csproj
@@ -8,7 +8,7 @@
 		<ProjectReference Include="..\..\Source\Mockolate.SourceGenerators\Mockolate.SourceGenerators.csproj"/>
 		<ProjectReference Include="..\..\Source\Mockolate\Mockolate.csproj"/>
 		<PackageReference Include="Microsoft.CodeAnalysis.Analyzers" PrivateAssets="all"/>
-		<PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all"/>
+		<PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all" VersionOverride="$(MinimumRoslynVersion)"/>
 	</ItemGroup>
 
 	<ItemGroup>