diff --git a/src/main/java/org/orekit/rugged/errors/RuggedMessages.java b/src/main/java/org/orekit/rugged/errors/RuggedMessages.java
index da289541206c49a5f409cd864ef8fd965996c4ba..972b11f3e444105142743857b6120f0d5a28faf6 100644
--- a/src/main/java/org/orekit/rugged/errors/RuggedMessages.java
+++ b/src/main/java/org/orekit/rugged/errors/RuggedMessages.java
@@ -116,7 +116,7 @@ public enum RuggedMessages implements Localizable {
                 final String translated = bundle.getString(name());
                 if ((translated != null) &&
                     (translated.length() > 0) &&
-                    (!translated.toLowerCase().contains("missing translation"))) {
+                    (!translated.toLowerCase(locale).contains("missing translation"))) {
                     // the value of the resource is the translated format
                     return translated;
                 }