diff --git a/xpfe/components/prefwindow/resources/locale/en-US/pref-images.dtd b/xpfe/components/prefwindow/resources/locale/en-US/pref-images.dtd
index 6ae20922b853..47bd43b08cac 100644
--- a/xpfe/components/prefwindow/resources/locale/en-US/pref-images.dtd
+++ b/xpfe/components/prefwindow/resources/locale/en-US/pref-images.dtd
@@ -7,7 +7,7 @@
     Place "&brandShortName;" in the phrase where the name of the application should
 	 appear
 -->
-<!ENTITY imageDetails                   "Specify how &brandShortName; handles images on webpages">
+<!ENTITY imageDetails                   "Specify how &brandShortName; handles images on webpages.">
 
 <!ENTITY accAllImagesRadio.label        "Accept all images">
 <!ENTITY accAllImagesRadio.accesskey    "i">