diff --git a/common/signature.cc b/common/signature.cc
index e497e780d..54d312777 100644
--- a/common/signature.cc
+++ b/common/signature.cc
@@ -327,7 +327,7 @@ absl::optional<TypeSpec> ParseBuiltinOrWrapper(std::string_view name_str) {
                     std::make_unique<TypeSpec>(DynTypeSpec())));
   }
 
-  return absl::nullopt;
+  return std::nullopt;
 }
 
 std::string Unescape(std::string_view str) {
diff --git a/internal/time.cc b/internal/time.cc
index 45945613d..c42212b68 100644
--- a/internal/time.cc
+++ b/internal/time.cc
@@ -42,7 +42,7 @@ absl::Duration MaxDuration() {
   // intent is to widen the CEL spec to support the larger range and match
   // google.protobuf.Duration from protocol buffer messages, which this
   // implementation currently supports.
-  // TODO(google/cel-spec/issues/214): revisit
+  // TODO(cel-expr/cel-spec/issues/214): revisit
   return absl::Seconds(google::protobuf::util::TimeUtil::kDurationMaxSeconds) +
          absl::Nanoseconds(google::protobuf::util::TimeUtil::kDurationMaxNanoseconds);
 }
@@ -52,7 +52,7 @@ absl::Duration MinDuration() {
   // intent is to widen the CEL spec to support the larger range and match
   // google.protobuf.Duration from protocol buffer messages, which this
   // implementation currently supports.
-  // TODO(google/cel-spec/issues/214): revisit
+  // TODO(cel-expr/cel-spec/issues/214): revisit
   return absl::Seconds(google::protobuf::util::TimeUtil::kDurationMinSeconds) +
          absl::Nanoseconds(google::protobuf::util::TimeUtil::kDurationMinNanoseconds);
 }