diff --git a/france/france_rsvp/codes.py b/france/france_rsvp/codes.py
new file mode 100644
index 0000000..e3759fb
--- /dev/null
+++ b/france/france_rsvp/codes.py
@@ -0,0 +1,56 @@
+import logging
+import random
+import sys
+
+from .database import get_db
+
+
+ALPHABET = '0123456789bcdefghjkmnpqrstuvwxyz'
+assert len(ALPHABET) == 32
+
+LENGTH = 4
+
+
+def list_errors(code):
+    for place in range(LENGTH):
+        for replacement in ALPHABET:
+            if replacement == code[place]:
+                continue
+            new_code = code[:place] + replacement + code[place + 1:]
+            yield new_code
+
+
+def main():
+    logging.basicConfig(level=logging.INFO)
+
+    if len(sys.argv) <= 1:
+        number = 1
+    elif len(sys.argv) == 2:
+        number = int(sys.argv[1], 10)
+    else:
+        raise ValueError
+
+    # Get the current codes
+    with get_db() as db:
+        correct_codes = set(row[0] for row in db.execute(
+            '''\
+            SELECT code FROM families;
+            ''',
+        ))
+
+    # Augment them with possible errored codes
+    errored_codes = set()
+    for code in correct_codes:
+        errored_codes.update(list_errors(code))
+    assert len(errored_codes) == LENGTH * (len(ALPHABET) - 1) * len(correct_codes)
+
+    # Generate new codes
+    generated = 0
+    while generated < number:
+        code = ''.join(random.choice(ALPHABET) for _ in range(LENGTH))
+        if code in correct_codes or code in errored_codes:
+            continue
+        correct_codes.add(code)
+        errored_codes.update(list_errors(code))
+        print(code)
+        generated += 1
diff --git a/france/pyproject.toml b/france/pyproject.toml
index f3e1117..b5169c6 100644
--- a/france/pyproject.toml
+++ b/france/pyproject.toml
@@ -15,6 +15,9 @@ uwsgi = ["uWSGI"]
 
 [tool.poetry.dev-dependencies]
 
+[tool.poetry.scripts]
+generate-codes = "france_rsvp.codes:main"
+
 [build-system]
 requires = ["poetry-core>=1.0.0"]
 build-backend = "poetry.core.masonry.api"
diff --git a/france/test-data.sql b/france/test-data.sql
index fc9582f..26e3db9 100644
--- a/france/test-data.sql
+++ b/france/test-data.sql
@@ -1,9 +1,9 @@
 INSERT INTO families(code, name) VALUES
-    ('aaaa', 'one'),
-    ('bbbb', 'two'),
-    ('cccc', 'three');
+    ('bbbb', 'one'),
+    ('cccc', 'two'),
+    ('dddd', 'three');
 
 INSERT INTO replies(family_code, date, adults, children) VALUES
-    ('aaaa', '2022-05-10 20:37:39', 2, 0),
-    ('aaaa', '2022-05-10 23:55:55', 0, 0),
-    ('bbbb', '2022-05-10 20:22:11', 2, 1);
+    ('bbbb', '2022-05-10 20:37:39', 2, 0),
+    ('bbbb', '2022-05-10 23:55:55', 0, 0),
+    ('cccc', '2022-05-10 20:22:11', 2, 1);