diff --git a/src/google/protobuf/compiler/csharp/BUILD.bazel b/src/google/protobuf/compiler/csharp/BUILD.bazel
index 96b8dcbc0e..414dd0ffd6 100644
--- a/src/google/protobuf/compiler/csharp/BUILD.bazel
+++ b/src/google/protobuf/compiler/csharp/BUILD.bazel
@@ -8,8 +8,8 @@ load("//build_defs:cpp_opts.bzl", "COPTS")
 
 cc_library(
     name = "names",
-    hdrs = ["names.h"],
     srcs = ["names.cc"],
+    hdrs = ["names.h"],
     copts = COPTS,
     include_prefix = "google/protobuf/compiler/csharp",
     visibility = ["//visibility:public"],
@@ -71,6 +71,7 @@ cc_library(
         ":names",
         "//src/google/protobuf:protobuf_nowkt",
         "//src/google/protobuf/compiler:code_generator",
+        "//src/google/protobuf/compiler:retention",
         "@com_google_absl//absl/container:flat_hash_set",
         "@com_google_absl//absl/strings",
     ],
@@ -125,9 +126,12 @@ pkg_files(
 
 filegroup(
     name = "test_srcs",
-    srcs = glob([
-        "*_test.cc",
-        "*unittest.cc",
-    ], allow_empty = True),
+    srcs = glob(
+        [
+            "*_test.cc",
+            "*unittest.cc",
+        ],
+        allow_empty = True,
+    ),
     visibility = ["//src/google/protobuf/compiler:__pkg__"],
 )
diff --git a/src/google/protobuf/compiler/csharp/csharp_helpers.cc b/src/google/protobuf/compiler/csharp/csharp_helpers.cc
index a08c1be084..2db328bc77 100644
--- a/src/google/protobuf/compiler/csharp/csharp_helpers.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_helpers.cc
@@ -56,6 +56,7 @@
 #include "google/protobuf/compiler/csharp/csharp_repeated_primitive_field.h"
 #include "google/protobuf/compiler/csharp/csharp_wrapper_field.h"
 #include "google/protobuf/compiler/csharp/names.h"
+#include "google/protobuf/compiler/retention.h"
 #include "google/protobuf/descriptor.pb.h"
 
 // Must be last.
@@ -380,8 +381,7 @@ std::string StringToBase64(absl::string_view input) {
 
 std::string FileDescriptorToBase64(const FileDescriptor* descriptor) {
   std::string fdp_bytes;
-  FileDescriptorProto fdp;
-  descriptor->CopyTo(&fdp);
+  FileDescriptorProto fdp = StripSourceRetentionOptions(*descriptor);
   fdp.SerializeToString(&fdp_bytes);
   return StringToBase64(fdp_bytes);
 }
diff --git a/src/google/protobuf/unittest_retention.proto b/src/google/protobuf/unittest_retention.proto
index e157bc452e..643cc35982 100644
--- a/src/google/protobuf/unittest_retention.proto
+++ b/src/google/protobuf/unittest_retention.proto
@@ -34,6 +34,7 @@ package protobuf_unittest;
 
 import "google/protobuf/descriptor.proto";
 
+option csharp_namespace = "ProtobufUnittest";
 
 // Retention attributes set directly on custom options
 extend google.protobuf.FileOptions {