diff --git a/csharp/src/Google.Protobuf.Benchmarks/Google.Protobuf.Benchmarks.csproj b/csharp/src/Google.Protobuf.Benchmarks/Google.Protobuf.Benchmarks.csproj
index ecc064ea7d..7432168210 100644
--- a/csharp/src/Google.Protobuf.Benchmarks/Google.Protobuf.Benchmarks.csproj
+++ b/csharp/src/Google.Protobuf.Benchmarks/Google.Protobuf.Benchmarks.csproj
@@ -3,6 +3,9 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>netcoreapp2.1</TargetFramework>
+    <AssemblyOriginatorKeyFile>../../keys/Google.Protobuf.snk</AssemblyOriginatorKeyFile>
+    <SignAssembly>true</SignAssembly>
+    <PublicSign Condition=" '$(OS)' != 'Windows_NT' ">true</PublicSign>
     <IsPackable>False</IsPackable>
   </PropertyGroup>
 
diff --git a/csharp/src/Google.Protobuf/Properties/AssemblyInfo.cs b/csharp/src/Google.Protobuf/Properties/AssemblyInfo.cs
index 9b179bd7cd..130bcf0004 100644
--- a/csharp/src/Google.Protobuf/Properties/AssemblyInfo.cs
+++ b/csharp/src/Google.Protobuf/Properties/AssemblyInfo.cs
@@ -47,3 +47,10 @@ using System.Security;
     "981207041fd5b2da3b498346fcfcd94910d52f25537c4a43ce3fbe17dc7d43e6cbdb4d8f1242dc" +
     "b6bd9b5906be74da8daa7d7280f97130f318a16c07baf118839b156299a48522f9fae2371c9665" +
     "c5ae9cb6")]
+
+[assembly: InternalsVisibleTo("Google.Protobuf.Benchmarks, PublicKey=" +
+    "002400000480000094000000060200000024000052534131000400000100010025800fbcfc63a1" +
+    "7c66b303aae80b03a6beaa176bb6bef883be436f2a1579edd80ce23edf151a1f4ced97af83abcd" +
+    "981207041fd5b2da3b498346fcfcd94910d52f25537c4a43ce3fbe17dc7d43e6cbdb4d8f1242dc" +
+    "b6bd9b5906be74da8daa7d7280f97130f318a16c07baf118839b156299a48522f9fae2371c9665" +
+    "c5ae9cb6")]