diff --git a/CHANGELOG b/CHANGELOG
index 3d20cca..883cff7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,6 @@
 Add timezone settings
 Combine Password reset and setting new nickname
+Add useful error message on failed login
 
 Version 1.17 - Apr. 20, 2016
 Make nocache refresh hack configurable in profile
diff --git a/chat.php b/chat.php
index 7046124..053412e 100644
--- a/chat.php
+++ b/chat.php
@@ -2015,7 +2015,7 @@ function write_new_session(){
 				$reentry=true;
 				break;
 			}else{
-				send_error($I['wrongpass']);
+				send_error("$I[userloggedin]<br>$I[wrongpass]");
 			}
 		}
 	}
@@ -2294,7 +2294,7 @@ function check_member(){
 			$stmt->execute(array($time, $U['nickname']));
 			return true;
 		}else{
-			send_error($I['wrongpass']);
+			send_error("$I[regednick]<br>$I[wrongpass]");
 		}
 	}
 	return false;
diff --git a/lang_de.php b/lang_de.php
index e2ea041..1b017db 100644
--- a/lang_de.php
+++ b/lang_de.php
@@ -337,6 +337,8 @@ $T=array(
 	'disabledtext' => 'Kurzzeitig deaktiviert',
 	'defaulttz' => 'Standard Zeitzone',
 	'tz' => 'Zeitzone',
-	'optional' => '(optional)'
+	'optional' => '(optional)',
+	'userloggedin' => 'Ein Nutzer mit diesem Nicknamen ist bereits angemeldet.',
+	'regednick' => 'Dieser Nickname ist ein registeriertes Mitglied.'
 );
 ?>
diff --git a/lang_en.php b/lang_en.php
index fcb9899..b01c900 100644
--- a/lang_en.php
+++ b/lang_en.php
@@ -337,6 +337,8 @@ $I=array(
 	'disabledtext' => 'Temporarily disabled',
 	'defaulttz' => 'Default time zone',
 	'tz' => 'Time zone',
-	'optional' => '(optional)'
+	'optional' => '(optional)',
+	'userloggedin' => 'A user with this nickname is already logged in.',
+	'regednick' => 'This nickname is a registered member.'
 );
 ?>