diff --git a/toolkit/content/widgets/datetimepicker.xml b/toolkit/content/widgets/datetimepicker.xml
index 117697541fa2..5cc52ab3b9c5 100644
--- a/toolkit/content/widgets/datetimepicker.xml
+++ b/toolkit/content/widgets/datetimepicker.xml
@@ -54,6 +54,7 @@
 
     <resources>
       <stylesheet src="chrome://global/skin/textbox.css"/>
+      <stylesheet src="chrome://global/skin/dropmarker.css"/>
       <stylesheet src="chrome://global/skin/datetimepicker.css"/>
     </resources>
 
@@ -1229,7 +1230,7 @@
       <xul:spinbuttons anonid="buttons" xbl:inherits="disabled" allowevents="true"
                        onup="this.parentNode._increaseOrDecrease(1);"
                        ondown="this.parentNode._increaseOrDecrease(-1);"/>
-      <xul:dropmarker class="datepicker-dropmarker"/>
+      <xul:dropmarker class="datepicker-dropmarker" xbl:inherits="disabled"/>
       <xul:menupopup>
         <xul:datepicker anonid="grid" type="grid" class="datepicker-popupgrid"
                         xbl:inherits="disabled,readonly,firstdayofweek"/>