diff --git a/src/main/scala/view/AvatarImageProvider.scala b/src/main/scala/view/AvatarImageProvider.scala
index c32091e..54fc9c2 100644
--- a/src/main/scala/view/AvatarImageProvider.scala
+++ b/src/main/scala/view/AvatarImageProvider.scala
@@ -17,7 +17,7 @@
       // by user name
       getAccountByUserName(userName).map { account =>
         if(account.image.isEmpty && getSystemSettings().gravatar){
-          s"""http://www.gravatar.com/avatar/${StringUtil.md5(account.mailAddress)}?s=${size}"""
+          s"""http://www.gravatar.com/avatar/${StringUtil.md5(account.mailAddress.toLowerCase)}?s=${size}"""
         } else {
           s"""${context.path}/${account.userName}/_avatar"""
         }
@@ -28,13 +28,13 @@
       // by mail address
       getAccountByMailAddress(mailAddress).map { account =>
         if(account.image.isEmpty && getSystemSettings().gravatar){
-          s"""http://www.gravatar.com/avatar/${StringUtil.md5(account.mailAddress)}?s=${size}"""
+          s"""http://www.gravatar.com/avatar/${StringUtil.md5(account.mailAddress.toLowerCase)}?s=${size}"""
         } else {
           s"""${context.path}/${account.userName}/_avatar"""
         }
       } getOrElse {
         if(mailAddress.nonEmpty && getSystemSettings().gravatar){
-          s"""http://www.gravatar.com/avatar/${StringUtil.md5(mailAddress)}?s=${size}"""
+          s"""http://www.gravatar.com/avatar/${StringUtil.md5(mailAddress.toLowerCase)}?s=${size}"""
         } else {
           s"""${context.path}/_unknown/_avatar"""
         }