diff --git a/dependency_support/load_external.bzl b/dependency_support/load_external.bzl
index 42fb946803..eb692fcfcd 100644
--- a/dependency_support/load_external.bzl
+++ b/dependency_support/load_external.bzl
@@ -228,7 +228,6 @@ def load_external_repositories():
     )
 
     # Released 2024-06-07, current as of 2024-06-26.
-    # TODO(google/xls#1408) Once updated, fix related TODOs.
     http_archive(
         name = "com_github_grpc_grpc",
         urls = ["https://github.com/grpc/grpc/archive/v1.64.2.tar.gz"],
diff --git a/xls/common/file/filesystem.cc b/xls/common/file/filesystem.cc
index 750123d54e..204be8ae89 100644
--- a/xls/common/file/filesystem.cc
+++ b/xls/common/file/filesystem.cc
@@ -62,15 +62,8 @@ class ParseTextProtoFileErrorCollector : public google::protobuf::io::ErrorColle
       const std::filesystem::path& file_name, const google::protobuf::Message& proto)
       : file_name_(file_name), proto_(proto) {}
 
-  // The Interface changed up-stream so this is an attempt to be
-  // compatible with older and newer versions. We can't add 'override' on any
-  // of the next two functions as it depends on the proto version we're using.
-
-  // New interface.
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, add 'override'.
-  // NOLINTNEXTLINE(modernize-use-override)
   void RecordError(int line, google::protobuf::io::ColumnNumber column,
-                   std::string_view message) /* override */ {
+                   std::string_view message) final {
     status_.Update(absl::Status(
         absl::StatusCode::kFailedPrecondition,
         absl::StrCat("Failed to parse ", proto_.GetDescriptor()->name(),
@@ -79,14 +72,6 @@ class ParseTextProtoFileErrorCollector : public google::protobuf::io::ErrorColle
                      "'.  Proto parser error:\n", message)));
   }
 
-  // Deprecated interface, compatible with older proto.
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, remove this method.
-  // NOLINTNEXTLINE(modernize-use-override)
-  void AddError(int line, int column,
-                const std::string& message) /* override */ {
-    RecordError(line, column, message);
-  }
-
   absl::Status status() const { return status_; }
 
  private:
diff --git a/xls/tools/proto_to_dslx.cc b/xls/tools/proto_to_dslx.cc
index 4bf8a4e948..779035e39b 100644
--- a/xls/tools/proto_to_dslx.cc
+++ b/xls/tools/proto_to_dslx.cc
@@ -241,39 +241,13 @@ std::string GetParentPrefixedName(const std::string& top_package,
 // SourceTreeDescriptorDatabase.
 class DbErrorCollector : public google::protobuf::compiler::MultiFileErrorCollector {
  public:
-  // Compatiblity: new interface is Record*(), old interface is Add*().
-  // For a transition period, be compatible with both, but note, we can't
-  // put 'override' on any of these depending on what version we're on.
-
-  // New interface.
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, add 'override'.
-  // NOLINTNEXTLINE(modernize-use-override)
   void RecordError(std::string_view filename, int line, int column,
-                   std::string_view message) /* override */ {
+                   std::string_view message) final {
     LOG(ERROR) << message;
   }
 
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, add 'override'.
-  // NOLINTNEXTLINE(modernize-use-override)
   void RecordWarning(std::string_view filename, int line, int column,
-                     std::string_view message) /* override */ {
-    LOG(WARNING) << message;
-  }
-
-  // Deprecated interface, compatible with older proto.
-  // Remove, once we're solidly on latest protobuf.
-
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, remove this method.
-  // NOLINTNEXTLINE(modernize-use-override)
-  void AddError(const std::string& filename, int line, int column,
-                const std::string& message) /* override */ {
-    LOG(ERROR) << message;
-  }
-
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, remove this method.
-  // NOLINTNEXTLINE(modernize-use-override)
-  void AddWarning(const std::string& filename, int line, int column,
-                  const std::string& message) /* override */ {
+                     std::string_view message) final {
     LOG(WARNING) << message;
   }
 };
@@ -281,41 +255,15 @@ class DbErrorCollector : public google::protobuf::compiler::MultiFileErrorCollec
 // Simple output logger for any errors coming from a DescriptorPool.
 class PoolErrorCollector : public DescriptorPool::ErrorCollector {
  public:
-  // Compatiblity: new interface is Record*(), old interface is Add*().
-  // For a transition period, be compatible with both, but note, we can't
-  // put 'override' on any of these depending on what version we're on.
-
-  // New interface.
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, add 'override'.
-  // NOLINTNEXTLINE(modernize-use-override)
   void RecordError(std::string_view filename, std::string_view element_name,
                    const Message* descriptor, ErrorLocation location,
-                   std::string_view message) /* override */ {
+                   std::string_view message) final {
     LOG(ERROR) << message;
   }
 
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, add 'override'.
-  // NOLINTNEXTLINE(modernize-use-override)
   void RecordWarning(std::string_view filename, std::string_view element_name,
                      const Message* descriptor, ErrorLocation location,
-                     std::string_view message) /* override */ {
-    LOG(WARNING) << message;
-  }
-
-  // Deprecated interface, compatible with older proto.
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, remove this method.
-  // NOLINTNEXTLINE(modernize-use-override)
-  void AddError(const std::string& filename, const std::string& element_name,
-                const Message* descriptor, ErrorLocation location,
-                const std::string& message) /* override */ {
-    LOG(ERROR) << message;
-  }
-
-  // TODO(google/xls#1408) Once grpc/protobuf is updated, remove this method.
-  // NOLINTNEXTLINE(modernize-use-override)
-  void AddWarning(const std::string& filename, const std::string& element_name,
-                  const Message* descriptor, ErrorLocation location,
-                  const std::string& message) /* override */ {
+                     std::string_view message) final {
     LOG(WARNING) << message;
   }
 };