diff --git a/src/calibre/gui2/convert/toc.ui b/src/calibre/gui2/convert/toc.ui
index 29fc2ec1ca..866b47625d 100644
--- a/src/calibre/gui2/convert/toc.ui
+++ b/src/calibre/gui2/convert/toc.ui
@@ -68,7 +68,7 @@
    <item row="7" column="0">
     <widget class="QLabel" name="label_16">
      <property name="text">
-      <string>Chapter &amp;threshold</string>
+      <string>Chapter &amp;threshold:</string>
      </property>
      <property name="buddy">
       <cstring>opt_toc_threshold</cstring>