diff --git a/src/calibre/db/cli/cmd_add.py b/src/calibre/db/cli/cmd_add.py
index bc2253e4ea..8c79a0f7bf 100644
--- a/src/calibre/db/cli/cmd_add.py
+++ b/src/calibre/db/cli/cmd_add.py
@@ -18,7 +18,7 @@ from calibre.srv.changes import books_added
 from calibre.utils.localization import canonicalize_lang
 
 readonly = False
-
+version = 0  # change this if you change signature of implementation()
 
 def to_stream(data):
     ans = BytesIO(data[1])
diff --git a/src/calibre/db/cli/cmd_add_format.py b/src/calibre/db/cli/cmd_add_format.py
index f516355f00..de4a3ade14 100644
--- a/src/calibre/db/cli/cmd_add_format.py
+++ b/src/calibre/db/cli/cmd_add_format.py
@@ -10,6 +10,7 @@ from io import BytesIO
 from calibre.srv.changes import formats_added
 
 readonly = False
+version = 0  # change this if you change signature of implementation()
 
 
 def implementation(db, notify_changes, book_id, data, fmt, replace):
diff --git a/src/calibre/db/cli/cmd_list.py b/src/calibre/db/cli/cmd_list.py
index 72e0262342..40f2165aac 100644
--- a/src/calibre/db/cli/cmd_list.py
+++ b/src/calibre/db/cli/cmd_list.py
@@ -15,6 +15,7 @@ from calibre.ebooks.metadata import authors_to_string
 from calibre.utils.date import isoformat
 
 readonly = True
+version = 0  # change this if you change signature of implementation()
 FIELDS = {
     'title', 'authors', 'author_sort', 'publisher', 'rating', 'timestamp', 'size',
     'tags', 'comments', 'series', 'series_index', 'formats', 'isbn', 'uuid',
diff --git a/src/calibre/db/cli/cmd_remove.py b/src/calibre/db/cli/cmd_remove.py
index 95bb6a1c8f..a73d955468 100644
--- a/src/calibre/db/cli/cmd_remove.py
+++ b/src/calibre/db/cli/cmd_remove.py
@@ -8,6 +8,7 @@ from calibre.db.delete_service import delete_service
 from calibre.srv.changes import books_deleted
 
 readonly = False
+version = 0  # change this if you change signature of implementation()
 
 
 def implementation(db, notify_changes, ids, permanent):