diff --git a/src/calibre/gui2/tweak_book/editor/smarts/html.py b/src/calibre/gui2/tweak_book/editor/smarts/html.py
index 9510e8e6c3..10f699c37e 100644
--- a/src/calibre/gui2/tweak_book/editor/smarts/html.py
+++ b/src/calibre/gui2/tweak_book/editor/smarts/html.py
@@ -613,7 +613,7 @@ class Smarts(NullSmarts):
     def auto_close_tag(self, editor):
         c = editor.textCursor()
         block, offset = c.block(), c.positionInBlock()
-        tag = find_closest_containing_tag(block, offset, max_tags=4000)
+        tag = find_closest_containing_tag(block, offset - 1, max_tags=4000)
         if tag is None:
             return False
         c.insertText('/%s>' % tag.name)