diff --git a/src/calibre/gui2/tweak_book/editor/syntax/html.py b/src/calibre/gui2/tweak_book/editor/syntax/html.py
index 25bcb3189b..5890481323 100644
--- a/src/calibre/gui2/tweak_book/editor/syntax/html.py
+++ b/src/calibre/gui2/tweak_book/editor/syntax/html.py
@@ -286,7 +286,7 @@ def closing_tag(state, text, i, formats):
def in_comment(state, text, i, formats):
' Comment, processing instruction or doctype '
end = {state.IN_COMMENT:'-->', state.IN_PI:'?>'}.get(state.parse, '>')
- pos = text.find(end, i+1)
+ pos = text.find(end, i)
fmt = formats['comment' if state.parse == state.IN_COMMENT else 'preproc']
if pos == -1:
num = len(text) - i
@@ -371,6 +371,8 @@ if __name__ == '__main__':
launch_editor('''\
+
A title with a tag <span> in it, the tag is treated as normal text