diff --git a/lib/constants.py b/lib/constants.py
index d30aeb7d9e59602e1ed407b4c1e9553ce4cf46d1..79d0b2fed0d3921cc3ba71d3c2a781702d804aa8 100644
--- a/lib/constants.py
+++ b/lib/constants.py
@@ -1703,3 +1703,6 @@ BLOCKDEV_DRIVER_MANUAL = "manual"
 HTOOLS = _autoconf.HTOOLS
 # The hail iallocator
 IALLOC_HAIL = "hail"
+
+# Do not re-export imported modules
+del re, _vcsversion, _autoconf
diff --git a/test/ganeti.constants_unittest.py b/test/ganeti.constants_unittest.py
index 9aab10fa1db2c565e01a4e32cad6e95eb71366d7..c0d834ccebb9f531e8644f533b3dc5d9bb8ea4ad 100755
--- a/test/ganeti.constants_unittest.py
+++ b/test/ganeti.constants_unittest.py
@@ -24,9 +24,11 @@
 
 import unittest
 import re
+import itertools
 
 from ganeti import constants
 from ganeti import locking
+from ganeti import utils
 
 import testutils
 
@@ -78,6 +80,25 @@ class TestConstants(unittest.TestCase):
     self.failUnless(constants.OP_PRIO_HIGH > constants.OP_PRIO_HIGHEST)
 
 
+class TestExportedNames(unittest.TestCase):
+  _VALID_NAME_RE = re.compile(r"^[A-Z][A-Z0-9_]+$")
+  _BUILTIN_NAME_RE = re.compile(r"^__\w+__$")
+  _EXCEPTIONS = frozenset([
+    "SplitVersion",
+    "BuildVersion",
+    ])
+
+  def test(self):
+    wrong = \
+      set(itertools.ifilterfalse(self._BUILTIN_NAME_RE.match,
+            itertools.ifilterfalse(self._VALID_NAME_RE.match,
+                                   dir(constants))))
+    wrong -= self._EXCEPTIONS
+    self.assertFalse(wrong,
+                     msg=("Invalid names exported from constants module: %s" %
+                          utils.CommaJoin(sorted(wrong))))
+
+
 class TestParameterNames(unittest.TestCase):
   """HV/BE parameter tests"""
   VALID_NAME = re.compile("^[a-zA-Z_][a-zA-Z0-9_]*$")