diff --git a/src/cmlxc/container.py b/src/cmlxc/container.py
index a5817e7..9301d18 100644
--- a/src/cmlxc/container.py
+++ b/src/cmlxc/container.py
@@ -538,7 +538,7 @@ def setup_repo(self, dest, out, source):
         name = dest.rsplit("/", 1)[-1]
         self.bash(f"rm -rf {dest}")
         out.print(f"  Initial clone of {name} ...")
-        self.bash(f"git clone {source.url} {dest}")
+        self.bash(f"git clone --branch {source.ref} {source.url} {dest}")
 
     def get_repo_status(self, repo_path):
         """Return a one-line string describing the git repo at repo_path."""
diff --git a/src/cmlxc/driver_base.py b/src/cmlxc/driver_base.py
index 914fb29..c6f7ea2 100644
--- a/src/cmlxc/driver_base.py
+++ b/src/cmlxc/driver_base.py
@@ -89,6 +89,7 @@ class Driver:
     DEFAULT_SOURCE_URL: str
     REPO_NAME: str
     REQUIRED_SOURCE_PATHS: list[str] = []
+    DEFAULT_REF: str = "main"
     type: str = "dns"
 
     def __init__(self, ct, out):
@@ -143,9 +144,9 @@ def add_cli_options(cls, parser, completer=None):
         """Register ``deploy-*`` CLI options on *parser*."""
         parser.add_argument(
             "--source",
-            default="@main",
+            default=f"@{cls.DEFAULT_REF}",
             metavar="SOURCE",
-            help="Driver source: @ref, /path, ./path, or URL@ref (default: @main).",
+            help=f"Driver source: @ref, /path, ./path, or URL@ref (default: @{cls.DEFAULT_REF}).",
         )
         action = parser.add_argument(
             "name",
@@ -220,7 +221,7 @@ def prep_builder(cls, ix, out, bld_ct):
 
         tmp_dest = f"/root/{cls.REPO_NAME}-git-main"
         if bld_ct.bash(f"test -d {tmp_dest}", check=False) is None:
-            source = parse_source("@main", cls.DEFAULT_SOURCE_URL)
+            source = parse_source(f"@{cls.DEFAULT_REF}", cls.DEFAULT_SOURCE_URL)
             bld_ct.setup_repo(tmp_dest, out, source)
         else:
             out.print(f"  Fetching {cls.REPO_NAME}-git-main from upstream ...")
diff --git a/src/cmlxc/driver_madmail.py b/src/cmlxc/driver_madmail.py
index e46f76b..6327f5b 100644
--- a/src/cmlxc/driver_madmail.py
+++ b/src/cmlxc/driver_madmail.py
@@ -22,6 +22,7 @@ class MadmailDriver(Driver):
     DEFAULT_SOURCE_URL = "https://github.com/themadorg/madmail.git"
     REPO_NAME = MADMAIL
     REQUIRED_SOURCE_PATHS = ["go.mod", "Makefile"]
+    DEFAULT_REF = "v0.47.1"
     type = "ipv4"
 
     @classmethod
diff --git a/tests/fullrun.py b/tests/fullrun.py
index 62e4116..9a4f6c6 100644
--- a/tests/fullrun.py
+++ b/tests/fullrun.py
@@ -126,7 +126,7 @@ def test_cm_ipv4_test():
 
 
 def test_mad_deploy():
-    cmlxc("deploy-madmail", "--source", "@main", CT_MAD)
+    cmlxc("deploy-madmail", CT_MAD)
 
 
 def test_mad_deploy_type():