diff --git a/common/values/parsed_map_field_value.cc b/common/values/parsed_map_field_value.cc
index e17bfb4d2..7324286fc 100644
--- a/common/values/parsed_map_field_value.cc
+++ b/common/values/parsed_map_field_value.cc
@@ -304,8 +304,9 @@ bool ValueToProtoMapKey(const Value& key,
     }
     case google::protobuf::FieldDescriptor::CPPTYPE_STRING: {
       if (auto string_key = key.AsString(); string_key) {
-        proto_key_scratch = string_key->NativeString();
-        proto_key->SetStringValue(proto_key_scratch);
+        // `google::protobuf::MapKey` does not own the string, which may be stored inline
+        // in `key` or in `proto_key_scratch`; `key` must not be moved.
+        proto_key->SetStringValue(string_key->ToStringView(&proto_key_scratch));
         return true;
       }
       return false;
diff --git a/common/values/struct_value_builder.cc b/common/values/struct_value_builder.cc
index d1e5b4882..1cb117f46 100644
--- a/common/values/struct_value_builder.cc
+++ b/common/values/struct_value_builder.cc
@@ -391,8 +391,9 @@ absl::StatusOr<absl::optional<ErrorValue>> ProtoStringMapKeyFromValueConverter(
     const Value& value, google::protobuf::MapKey& key, std::string& key_string,
     google::protobuf::Arena* absl_nonnull arena) {
   if (auto string_value = value.AsString(); string_value) {
-    key_string = string_value->NativeString();
-    key.SetStringValue(key_string);
+    // `google::protobuf::MapKey` does not own the string, which may be stored inline in
+    // `value` or in `key_string`; `value` must not be moved.
+    key.SetStringValue(string_value->ToStringView(&key_string));
     return std::nullopt;
   }
   return TypeConversionError(value.GetTypeName(), "string", arena);
diff --git a/eval/public/containers/internal_field_backed_map_impl.cc b/eval/public/containers/internal_field_backed_map_impl.cc
index 2d5666c58..e4569aa82 100644
--- a/eval/public/containers/internal_field_backed_map_impl.cc
+++ b/eval/public/containers/internal_field_backed_map_impl.cc
@@ -174,7 +174,6 @@ absl::StatusOr<bool> FieldBackedMapImpl::LookupMapValue(
     return InvalidMapKeyType(key_desc_->cpp_type_name());
   }
 
-  std::string map_key_string;
   google::protobuf::MapKey proto_key;
   switch (key_desc_->cpp_type()) {
     case google::protobuf::FieldDescriptor::CPPTYPE_BOOL: {
@@ -199,8 +198,7 @@ absl::StatusOr<bool> FieldBackedMapImpl::LookupMapValue(
     case google::protobuf::FieldDescriptor::CPPTYPE_STRING: {
       CelValue::StringHolder key_value;
       key.GetValue(&key_value);
-      map_key_string.assign(key_value.value().data(), key_value.value().size());
-      proto_key.SetStringValue(map_key_string);
+      proto_key.SetStringValue(key_value.value());
     } break;
     case google::protobuf::FieldDescriptor::CPPTYPE_UINT32: {
       uint64_t key_value;
diff --git a/eval/public/structs/cel_proto_wrap_util.cc b/eval/public/structs/cel_proto_wrap_util.cc
index 87d05ee3f..08d716d46 100644
--- a/eval/public/structs/cel_proto_wrap_util.cc
+++ b/eval/public/structs/cel_proto_wrap_util.cc
@@ -111,7 +111,7 @@ class DynamicMap : public CelMap {
           "Invalid map key type: '", CelValue::TypeName(key.type()), "'"));
     }
 
-    return values_->fields().contains(std::string(str_key.value()));
+    return values_->fields().contains(str_key.value());
   }
 
   absl::optional<CelValue> operator[](CelValue key) const override;
@@ -692,7 +692,7 @@ absl::optional<CelValue> DynamicMap::operator[](CelValue key) const {
                                         CelValue::TypeName(key.type()), "'")));
   }
 
-  auto it = values_->fields().find(std::string(str_key.value()));
+  auto it = values_->fields().find(str_key.value());
   if (it == values_->fields().end()) {
     return std::nullopt;
   }
diff --git a/extensions/protobuf/internal/qualify.cc b/extensions/protobuf/internal/qualify.cc
index 1d53dac0d..7c1503d1c 100644
--- a/extensions/protobuf/internal/qualify.cc
+++ b/extensions/protobuf/internal/qualify.cc
@@ -104,7 +104,6 @@ absl::StatusOr<absl::optional<google::protobuf::MapValueConstRef>> LookupMapValu
         key_desc->cpp_type_name());
   }
 
-  std::string proto_key_string;
   google::protobuf::MapKey proto_key;
   switch (key_desc->cpp_type()) {
     case google::protobuf::FieldDescriptor::CPPTYPE_BOOL:
@@ -122,8 +121,7 @@ absl::StatusOr<absl::optional<google::protobuf::MapValueConstRef>> LookupMapValu
       proto_key.SetInt64Value(*key.GetInt64Key());
       break;
     case google::protobuf::FieldDescriptor::CPPTYPE_STRING: {
-      proto_key_string = std::string(*key.GetStringKey());
-      proto_key.SetStringValue(proto_key_string);
+      proto_key.SetStringValue(*key.GetStringKey());
     } break;
     case google::protobuf::FieldDescriptor::CPPTYPE_UINT32: {
       uint64_t key_value = *key.GetUint64Key();
diff --git a/extensions/select_optimization.cc b/extensions/select_optimization.cc
index 5244907e6..8e1a95440 100644
--- a/extensions/select_optimization.cc
+++ b/extensions/select_optimization.cc
@@ -270,7 +270,8 @@ absl::StatusOr<Value> MapKeyFromQualifier(const AttributeQualifier& qual,
     case Kind::kBool:
       return cel::BoolValue(*qual.GetBoolKey());
     case Kind::kString:
-      return StringValue::From(*qual.GetStringKey(), arena);
+      // Safe as `qual` is valid for the lifetime of the expression/program.
+      return StringValue::WrapUnsafe(*qual.GetStringKey());
     default:
       return runtime_internal::CreateNoMatchingOverloadError(
           cel::builtin::kIndex);