diff --git a/src/calibre/gui2/convert/regex_builder.py b/src/calibre/gui2/convert/regex_builder.py
index eac54b9825..0ef3a2fa2a 100644
--- a/src/calibre/gui2/convert/regex_builder.py
+++ b/src/calibre/gui2/convert/regex_builder.py
@@ -206,6 +206,7 @@ class RegexEdit(QWidget, Ui_Edit):
     def __init__(self, parent=None):
         QWidget.__init__(self, parent)
         self.setupUi(self)
+        self.edit.completer().setCaseSensitivity(Qt.CaseSensitive)
 
         self.book_id = None
         self.db = None