diff --git a/internal/platform/ble_v2.h b/internal/platform/ble_v2.h
index 41099ace..e3d8fe7c 100644
--- a/internal/platform/ble_v2.h
+++ b/internal/platform/ble_v2.h
@@ -280,7 +280,7 @@ class GattClient final {
 
   // NOLINTNEXTLINE(google3-legacy-absl-backports)
   absl::optional<std::string> ReadCharacteristic(
-      api::ble_v2::GattCharacteristic& characteristic) {
+      const api::ble_v2::GattCharacteristic& characteristic) {
     return impl_->ReadCharacteristic(characteristic);
   }