diff --git a/resources/default_tweaks.py b/resources/default_tweaks.py
index 1cf699efa3..c4c951f980 100644
--- a/resources/default_tweaks.py
+++ b/resources/default_tweaks.py
@@ -88,13 +88,6 @@ categories_collapsed_rating_template = r'{first.avg_rating:4.2f:ifempty(0)} - {l
 categories_collapsed_popularity_template = r'{first.count:d} - {last.count:d}'
 
 
-#: Set boolean custom columns to be tristate
-# Set whether boolean custom columns are two- or three-valued.
-#  Two-values for true booleans
-#  three-values for yes/no/unknown
-# Set to 'yes' for three-values, 'no' for two-values
-bool_custom_columns_are_tristate = 'yes'
-
 #: Specify columns to sort the booklist by on startup
 # Provide a set of columns to be sorted on when calibre starts
 #  The argument is None if saved sort history is to be used
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index b05e029c38..50ecc4f1e5 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -213,6 +213,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         defs['gui_restriction'] = defs['cs_restriction'] = ''
         defs['categories_using_hierarchy'] = []
 
+        # Migrate the bool tristate tweak
         defs['bools_are_tristate'] = \
                 tweaks.get('bool_custom_columns_are_tristate', 'yes') == 'yes'
         if self.prefs.get('bools_are_tristate') is None: