diff --git a/letsencrypt/plugins/common.py b/letsencrypt/plugins/common.py
index 39956fc90..bef8b4d81 100644
--- a/letsencrypt/plugins/common.py
+++ b/letsencrypt/plugins/common.py
@@ -20,7 +20,7 @@ def option_namespace(name):
 
 def dest_namespace(name):
     """ArgumentParser dest namespace (prefix of all destinations)."""
-    return name + "_"
+    return name.replace("-", "_") + "_"
 
 private_ips_regex = re.compile(  # pylint: disable=invalid-name
     r"(^127\.0\.0\.1)|(^10\.)|(^172\.1[6-9]\.)|"
diff --git a/letsencrypt/plugins/common_test.py b/letsencrypt/plugins/common_test.py
index 16d653631..fa761839c 100644
--- a/letsencrypt/plugins/common_test.py
+++ b/letsencrypt/plugins/common_test.py
@@ -23,6 +23,10 @@ class NamespaceFunctionsTest(unittest.TestCase):
         from letsencrypt.plugins.common import dest_namespace
         self.assertEqual("foo_", dest_namespace("foo"))
 
+    def test_dest_namespace_with_dashes(self):
+        from letsencrypt.plugins.common import dest_namespace
+        self.assertEqual("foo_bar_", dest_namespace("foo-bar"))
+
 
 class PluginTest(unittest.TestCase):
     """Test for letsencrypt.plugins.common.Plugin."""