diff --git a/src/calibre/gui2/dialogs/metadata_bulk.py b/src/calibre/gui2/dialogs/metadata_bulk.py
index dba1080c04..0a27bb1351 100644
--- a/src/calibre/gui2/dialogs/metadata_bulk.py
+++ b/src/calibre/gui2/dialogs/metadata_bulk.py
@@ -975,7 +975,7 @@ class MetadataBulkDialog(QDialog, Ui_MetadataBulkDialog):
         self.s_r_set_colors()
         flags = regex.FULLCASE | regex.UNICODE
 
-        if self.case_sensitive.isChecked():
+        if not self.case_sensitive.isChecked():
             flags |= regex.IGNORECASE
 
         try: