diff --git a/pyproject.toml b/pyproject.toml
index f313f8576f..6d7ddbc87b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -61,7 +61,7 @@ unfixable = ['PIE794', 'ISC001']
 "src/calibre/gui2/store/stores/*" = ['UP']
 "src/calibre/gui2/tts/manager.py" = ['UP037']
 "src/calibre/utils/copy_files.py" = ['UP037']
-"src/calibre/utils/smartypants.py" = ['RUF039', 'RUF055']
+"src/calibre/utils/smartypants.py" = ['RUF055']
 "src/calibre/web/feeds/news.py" = ['RET501']
 "src/qt/*.py" = ['I', 'E302']
 "src/qt/*.pyi" = ['I']
diff --git a/src/calibre/utils/smartypants.py b/src/calibre/utils/smartypants.py
index cf943d2cf9..3a5d72facd 100644
--- a/src/calibre/utils/smartypants.py
+++ b/src/calibre/utils/smartypants.py
@@ -493,7 +493,7 @@ def smartyPants(text, attr='1'):
             if not in_pre:
                 t = processEscapes(t)
 
-                t = re.sub('"', '"', t)
+                t = re.sub(r'"', '"', t)
                 t = dashes_func(t)
                 t = ellipses_func(t)
                 # Note: backticks need to be processed before quotes.