diff --git a/csharp/src/Google.Protobuf/Google.Protobuf.csproj b/csharp/src/Google.Protobuf/Google.Protobuf.csproj
index cf30e4a84e..4eebd99eee 100644
--- a/csharp/src/Google.Protobuf/Google.Protobuf.csproj
+++ b/csharp/src/Google.Protobuf/Google.Protobuf.csproj
@@ -18,6 +18,7 @@
     <RepositoryType>git</RepositoryType>
     <RepositoryUrl>https://github.com/nodatime/nodatime.git</RepositoryUrl>
     <IncludeSymbols>true</IncludeSymbols>
+    <IncludeSource>true</IncludeSource>
   </PropertyGroup>
 
   <!--