diff --git a/HTTP.java b/HTTP.java
index b14d04ec9..9b444cec3 100644
--- a/HTTP.java
+++ b/HTTP.java
@@ -25,6 +25,7 @@ of this software and associated documentation files (the "Software"), to deal
 */
 
 import java.util.Iterator;
+import java.util.Locale;
 
 /**
  * Convert an HTTP header to a JSONObject and back.
@@ -74,7 +75,7 @@ public static JSONObject toJSONObject(String string) throws JSONException {
         String         token;
 
         token = x.nextToken();
-        if (token.toUpperCase().startsWith("HTTP")) {
+        if (token.toUpperCase(Locale.ROOT).startsWith("HTTP")) {
 
 // Response
 
diff --git a/JSONObject.java b/JSONObject.java
index 4df256a3b..1eab69404 100644
--- a/JSONObject.java
+++ b/JSONObject.java
@@ -1157,9 +1157,9 @@ private void populateMap(Object bean) {
                             && Character.isUpperCase(key.charAt(0))
                             && method.getParameterTypes().length == 0) {
                         if (key.length() == 1) {
-                            key = key.toLowerCase();
+                            key = key.toLowerCase(Locale.ROOT);
                         } else if (!Character.isUpperCase(key.charAt(1))) {
-                            key = key.substring(0, 1).toLowerCase()
+                            key = key.substring(0, 1).toLowerCase(Locale.ROOT)
                                     + key.substring(1);
                         }