diff --git a/engine/src/flutter/runtime/dart_service_isolate.cc b/engine/src/flutter/runtime/dart_service_isolate.cc
index 218c3bb6035..5632738a108 100644
--- a/engine/src/flutter/runtime/dart_service_isolate.cc
+++ b/engine/src/flutter/runtime/dart_service_isolate.cc
@@ -76,7 +76,7 @@ void DartServiceIsolate::NotifyServerState(Dart_NativeArguments args) {
     }
   }
 
-  for (auto callback_to_fire : callbacks_to_fire) {
+  for (const auto& callback_to_fire : callbacks_to_fire) {
     callback_to_fire(uri);
   }
 }
diff --git a/engine/src/flutter/third_party/txt/src/txt/font_collection.cc b/engine/src/flutter/third_party/txt/src/txt/font_collection.cc
index 3b550f7f313..c35c10a95f7 100644
--- a/engine/src/flutter/third_party/txt/src/txt/font_collection.cc
+++ b/engine/src/flutter/third_party/txt/src/txt/font_collection.cc
@@ -151,7 +151,7 @@ FontCollection::GetMinikinFontCollectionForFamilies(
   // Search for default font family if no user font families were found.
   if (minikin_families.empty()) {
     const auto default_font_families = GetDefaultFontFamilies();
-    for (auto family : default_font_families) {
+    for (const auto& family : default_font_families) {
       std::shared_ptr<minikin::FontFamily> minikin_family =
           FindFontFamilyInManagers(family);
       if (minikin_family != nullptr) {
@@ -166,7 +166,8 @@ FontCollection::GetMinikinFontCollectionForFamilies(
     return nullptr;
   }
   if (enable_font_fallback_) {
-    for (std::string fallback_family : fallback_fonts_for_locale_[locale]) {
+    for (const std::string& fallback_family :
+         fallback_fonts_for_locale_[locale]) {
       auto it = fallback_fonts_.find(fallback_family);
       if (it != fallback_fonts_.end()) {
         minikin_families.push_back(it->second);
diff --git a/engine/src/flutter/third_party/txt/src/txt/font_features.cc b/engine/src/flutter/third_party/txt/src/txt/font_features.cc
index 0729a035aa9..0b7b6abdc2b 100644
--- a/engine/src/flutter/third_party/txt/src/txt/font_features.cc
+++ b/engine/src/flutter/third_party/txt/src/txt/font_features.cc
@@ -30,7 +30,7 @@ std::string FontFeatures::GetFeatureSettings() const {
 
   std::ostringstream stream;
 
-  for (auto kv : feature_map_) {
+  for (const auto& kv : feature_map_) {
     if (stream.tellp()) {
       stream << ',';
     }