diff --git a/www/tiqr/locales/en.yml b/www/tiqr/locales/en.yml
index c2e8e57d..39686512 100644
--- a/www/tiqr/locales/en.yml
+++ b/www/tiqr/locales/en.yml
@@ -14,9 +14,13 @@ login:
             message: If the instructions on your phone instruct you to login manually, click %link_start%here%link_end%.
             userid: User ID
             otp: One time password
-            button: Go
+            button: Ok
         no_account: No account yet? Please create a new account %link_start%here%link_end%.
     cancel: Cancel
+    error:
+        invalid_challenge: Invalid challenge - please reload this page and try again.
+        invalid_response: Invalid response - have you entered the correct PIN?
+
 enrol:
     title: Register new Tiqr account
     status:
diff --git a/www/tiqr/locales/nl.yml b/www/tiqr/locales/nl.yml
index f7e067b3..d44f1bf5 100644
--- a/www/tiqr/locales/nl.yml
+++ b/www/tiqr/locales/nl.yml
@@ -14,9 +14,12 @@ login:
             message: Krijg je een melding op je telefoon om handmatig in te loggen? Klik dan %link_start%hier%link_end%.
             userid: User ID
             otp: One time password
-            button: Go
+            button: Ok
         no_account: Geen account? Maak er dan %link_start%hier%link_end% eerst een aan.
     cancel: Annuleren
+    error:
+        invalid_challenge: ongeldig - herlaad deze pagina en probeer opnieuw.
+        invalid_response: ongeldig one time password - heb je de juiste PIN ingevoerd?
 enrol:
     title: Registreer nieuw Tiqr-account
     status:
diff --git a/www/tiqr/views/index.html b/www/tiqr/views/index.html
index 0ebb0c7e..97f70488 100644
--- a/www/tiqr/views/index.html
+++ b/www/tiqr/views/index.html
@@ -28,6 +28,11 @@
         });
     }
     jQuery(document).ready(verifyLogin);
+
+    var errors = {
+	INVALID_CHALLENGE:"{{ 'error.invalid_challenge' | trans }}",
+	INVALID_RESPONSE:"{{ 'error.invalid_response' | trans }}"
+    }
 </script>
 
 <div class="container">
@@ -110,7 +115,7 @@ <h2>{{ 'login.title' | trans }}</h2>
             $.post(url, request,
                     function(data){
                         if( data != "OK" )
-                            $( "#result" ).empty().append( "Error: " + data );
+                            $( "#result" ).empty().append( "Error: " + errors[data] );
                     });
         });