diff --git a/csharp/src/Google.Protobuf.Test/testprotos.pb b/csharp/src/Google.Protobuf.Test/testprotos.pb
index 6e2d20e54f..8e3aa4b0ae 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 fabd248982..e7bc8441de 100644
--- a/csharp/src/Google.Protobuf/Reflection/Descriptor.pb.cs
+++ b/csharp/src/Google.Protobuf/Reflection/Descriptor.pb.cs
@@ -6031,12 +6031,16 @@ namespace Google.Protobuf.Reflection {
 
     private bool javaStringCheckUtf8_;
     /// <summary>
-    /// If set true, then the Java2 code generator will generate code that
-    /// throws an exception whenever an attempt is made to assign a non-UTF-8
-    /// byte sequence to a string field.
-    /// Message reflection will do the same.
-    /// However, an extension field still accepts non-UTF-8 byte sequences.
-    /// This option has no effect on when used with the lite runtime.
+    /// A proto2 file can set this to true to opt in to UTF-8 checking for Java,
+    /// which will throw an exception if invalid UTF-8 is parsed from the wire or
+    /// assigned to a string field.
+    ///
+    /// TODO: clarify exactly what kinds of field types this option
+    /// applies to, and update these docs accordingly.
+    ///
+    /// Proto3 files already perform these checks. Setting the option explicitly to
+    /// false has no effect: it cannot be used to opt proto3 files out of UTF-8
+    /// checks.
     /// </summary>
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]