diff --git a/src/calibre/ebooks/conversion/utils.py b/src/calibre/ebooks/conversion/utils.py
index e8e2a82949..c0c2ee8978 100644
--- a/src/calibre/ebooks/conversion/utils.py
+++ b/src/calibre/ebooks/conversion/utils.py
@@ -149,17 +149,17 @@ class HeuristicProcessor(object):
         ]
 
         ITALICIZE_STYLE_PATS = [
-            r'(?msu)(?<=[\s>"])_(?P<words>[^_]+)?_',
-            r'(?msu)(?<=[\s>"])/(?P<words>[^/]+)?/',
-            r'(?msu)(?<=[\s>"])~~(?P<words>[^~]+)?~~',
-            r'(?msu)(?<=[\s>"])\*(?P<words>[^\*]+)?\*',
-            r'(?msu)(?<=[\s>"])~(?P<words>[^~]+)?~',
-            r'(?msu)(?<=[\s>"])_/(?P<words>[^/_]+)?/_',
-            r'(?msu)(?<=[\s>"])_\*(?P<words>[^\*_]+)?\*_',
-            r'(?msu)(?<=[\s>"])\*/(?P<words>[^/\*]+)?/\*',
-            r'(?msu)(?<=[\s>"])_\*/(?P<words>[^\*_]+)?/\*_',
-            r'(?msu)(?<=[\s>"])/:(?P<words>[^:/]+)?:/',
-            r'(?msu)(?<=[\s>"])\|:(?P<words>[^:\|]+)?:\|',
+            r'(?msu)(?<=[\s>])_(?P<words>[^_]+)?_',
+            r'(?msu)(?<=[\s>])/(?P<words>[^/]+)?/',
+            r'(?msu)(?<=[\s>])~~(?P<words>[^~]+)?~~',
+            r'(?msu)(?<=[\s>])\*(?P<words>[^\*]+)?\*',
+            r'(?msu)(?<=[\s>])~(?P<words>[^~]+)?~',
+            r'(?msu)(?<=[\s>])_/(?P<words>[^/_]+)?/_',
+            r'(?msu)(?<=[\s>])_\*(?P<words>[^\*_]+)?\*_',
+            r'(?msu)(?<=[\s>])\*/(?P<words>[^/\*]+)?/\*',
+            r'(?msu)(?<=[\s>])_\*/(?P<words>[^\*_]+)?/\*_',
+            r'(?msu)(?<=[\s>])/:(?P<words>[^:/]+)?:/',
+            r'(?msu)(?<=[\s>])\|:(?P<words>[^:\|]+)?:\|',
         ]
 
         for word in ITALICIZE_WORDS: