diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 85b0fd274b..2c09337f10 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -582,7 +582,7 @@ en:
     suggested_topics: "The number of suggested topics shown at the bottom of a topic"
 
     enable_s3_uploads: "Place uploads on Amazon S3"
-    s3_upload_bucket: "The Amazon S3 bucket name that files will be uploaded into"
+    s3_upload_bucket: "The Amazon S3 bucket name that files will be uploaded into. WARNING: must be lowercase (cf. http://docs.aws.amazon.com/AmazonS3/latest/dev/BucketRestrictions.html)"
     s3_access_key_id: "The Amazon S3 access key id that will be used to upload images"
     s3_secret_access_key: "The Amazon S3 secret access key that will be used to upload images"
     s3_region: "The Amazon S3 region name that will be used to upload images"
diff --git a/config/locales/server.fr.yml b/config/locales/server.fr.yml
index 00be8d3212..05dd3a0c31 100644
--- a/config/locales/server.fr.yml
+++ b/config/locales/server.fr.yml
@@ -551,7 +551,7 @@ fr:
     suggested_topics: "Nombre de discussions suggerées en dessous d'une discussion"
 
     enable_s3_uploads: "S'il faut ou non uploader sur s3"
-    s3_upload_bucket: "Le bucket dans lequel uploader sur s3"
+    s3_upload_bucket: "Le nom du bucket s3 où seront uploader les fichiers. ATTENTION : le nom doit être en minuscule (cf. http://docs.aws.amazon.com/AmazonS3/latest/dev/BucketRestrictions.html)"
     s3_secret_access_key: "La clé secrète Amazon S3 qui va être utilisée pour uploader des images"
     s3_region: "Le nom de la région Amazon S3 qui va être utilisée pour uploader des images"