diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index d7bb251506..075f337765 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -341,7 +341,9 @@ class DB(object):
                                 if f['is_custom']]
                 for f in fmvals:
                     self.create_custom_column(f['label'], f['name'],
-                            f['datatype'], f['is_multiple'] is not None,
+                            f['datatype'],
+                            (f['is_multiple'] is not None and
+                                len(f['is_multiple']) > 0),
                             f['is_editable'], f['display'])
 
         defs = self.prefs.defaults
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index 9c08e78011..fcf3cc5d76 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -214,7 +214,8 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
                 fmvals = [f for f in default_prefs['field_metadata'].values() if f['is_custom']]
                 for f in fmvals:
                     self.create_custom_column(f['label'], f['name'], f['datatype'],
-                            f['is_multiple'] is not None, f['is_editable'], f['display'])
+                            f['is_multiple'] is not None and len(f['is_multiple']) > 0,
+                            f['is_editable'], f['display'])
         self.initialize_dynamic()
 
     def get_property(self, idx, index_is_id=False, loc=-1):