diff --git a/csharp/src/Google.Protobuf.Test/testprotos.pb b/csharp/src/Google.Protobuf.Test/testprotos.pb
index 9527755cf1..a33cfa7081 100644
Binary files a/csharp/src/Google.Protobuf.Test/testprotos.pb and b/csharp/src/Google.Protobuf.Test/testprotos.pb differ
diff --git a/csharp/src/Google.Protobuf/Reflection/Descriptor.pb.cs b/csharp/src/Google.Protobuf/Reflection/Descriptor.pb.cs
index 2421d98c05..208e5fe648 100644
--- a/csharp/src/Google.Protobuf/Reflection/Descriptor.pb.cs
+++ b/csharp/src/Google.Protobuf/Reflection/Descriptor.pb.cs
@@ -3387,12 +3387,12 @@ namespace Google.Protobuf.Reflection {
     /// If true, this is a proto3 "optional". When a proto3 field is optional, it
     /// tracks presence regardless of field type.
     ///
-    /// When proto3_optional is true, this field must be belong to a oneof to
-    /// signal to old proto3 clients that presence is tracked for this field. This
-    /// oneof is known as a "synthetic" oneof, and this field must be its sole
-    /// member (each proto3 optional field gets its own synthetic oneof). Synthetic
-    /// oneofs exist in the descriptor only, and do not generate any API. Synthetic
-    /// oneofs must be ordered after all "real" oneofs.
+    /// When proto3_optional is true, this field must belong to a oneof to signal
+    /// to old proto3 clients that presence is tracked for this field. This oneof
+    /// is known as a "synthetic" oneof, and this field must be its sole member
+    /// (each proto3 optional field gets its own synthetic oneof). Synthetic oneofs
+    /// exist in the descriptor only, and do not generate any API. Synthetic oneofs
+    /// must be ordered after all "real" oneofs.
     ///
     /// For message fields, proto3_optional doesn't create any semantic change,
     /// since non-repeated message fields always track presence. However it still