diff --git a/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManagerBase.java b/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManagerBase.java
index 78b90baddd1..ab96ecfdfdd 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManagerBase.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManagerBase.java
@@ -198,7 +198,7 @@ public abstract class DevSupportManagerBase implements DevSupportManager {
     final String bundleFile = subclassTag + "ReactNativeDevBundle.js";
     mJSBundleDownloadedFile = new File(applicationContext.getFilesDir(), bundleFile);
 
-    final String splitBundlesDir = subclassTag.toLowerCase() + "_dev_js_split_bundles";
+    final String splitBundlesDir = subclassTag.toLowerCase(Locale.ROOT) + "_dev_js_split_bundles";
     mJSSplitBundlesDir = mApplicationContext.getDir(splitBundlesDir, Context.MODE_PRIVATE);
 
     mDefaultNativeModuleCallExceptionHandler = new DefaultNativeModuleCallExceptionHandler();
diff --git a/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkingModule.java b/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkingModule.java
index 55cfb20215a..f80b1c65618 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkingModule.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkingModule.java
@@ -30,6 +30,7 @@ import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import okhttp3.Call;
@@ -376,7 +377,9 @@ public final class NetworkingModule extends NativeNetworkingAndroidSpec {
     }
 
     RequestBody requestBody;
-    if (data == null || method.toLowerCase().equals("get") || method.toLowerCase().equals("head")) {
+    if (data == null
+        || method.toLowerCase(Locale.ROOT).equals("get")
+        || method.toLowerCase(Locale.ROOT).equals("head")) {
       requestBody = RequestBodyUtil.getEmptyBody(method);
     } else if (handler != null) {
       requestBody = handler.toRequestBody(data, contentType);
diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/imagehelper/ResourceDrawableIdHelper.java b/ReactAndroid/src/main/java/com/facebook/react/views/imagehelper/ResourceDrawableIdHelper.java
index 804e9d7b023..8053ece767a 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/imagehelper/ResourceDrawableIdHelper.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/imagehelper/ResourceDrawableIdHelper.java
@@ -12,6 +12,7 @@ import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import androidx.annotation.Nullable;
 import java.util.HashMap;
+import java.util.Locale;
 import java.util.Map;
 import javax.annotation.concurrent.ThreadSafe;
 
@@ -47,7 +48,7 @@ public class ResourceDrawableIdHelper {
     if (name == null || name.isEmpty()) {
       return 0;
     }
-    name = name.toLowerCase().replace("-", "_");
+    name = name.toLowerCase(Locale.ROOT).replace("-", "_");
 
     // name could be a resource id.
     try {
diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputManager.java b/ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputManager.java
index df6cc09407b..99ae31e7d50 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputManager.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputManager.java
@@ -75,6 +75,7 @@ import com.facebook.yoga.YogaConstants;
 import java.lang.reflect.Field;
 import java.util.HashMap;
 import java.util.LinkedList;
+import java.util.Locale;
 import java.util.Map;
 
 /** Manages instances of TextInput. */
@@ -569,7 +570,7 @@ public class ReactTextInputManager extends BaseViewManager<ReactEditText, Layout
   }
 
   private static boolean shouldHideCursorForEmailTextInput() {
-    String manufacturer = Build.MANUFACTURER.toLowerCase();
+    String manufacturer = Build.MANUFACTURER.toLowerCase(Locale.ROOT);
     return (Build.VERSION.SDK_INT == Build.VERSION_CODES.Q && manufacturer.contains("xiaomi"));
   }