diff --git a/src/calibre/devices/kindle/driver.py b/src/calibre/devices/kindle/driver.py
index 2f036e4b4e..4a5b9e117f 100644
--- a/src/calibre/devices/kindle/driver.py
+++ b/src/calibre/devices/kindle/driver.py
@@ -377,8 +377,8 @@ class KINDLE2(KINDLE):
             ' default one selected above.  Specify the name of the custom'
             ' column here, for example, #pagemethod. The custom column should have the '
             ' values: fast, accurate or pagebreak.'),
-        _('Overwrite existing apnx on device') + ':::' + _(
-            'Uncheck this option to allow an apnx file existing on the device'
+        _('Overwrite existing APNX on device') + ':::' + _(
+            'Uncheck this option to allow an APNX file existing on the device'
             ' to have priority over the version which calibre would send.'
             ' Since APNX files are usually deleted when a book is removed from'
             ' the Kindle, this is mostly useful when resending a book to the'