diff --git a/tempest/test.py b/tempest/test.py
index 38b9102..984d5ca 100644
--- a/tempest/test.py
+++ b/tempest/test.py
@@ -148,6 +148,8 @@
             else:
                 skip = True
             if "bug" in kwargs and skip is True:
+                if not kwargs['bug'].isdigit():
+                    raise ValueError('bug must be a valid bug number')
                 msg = "Skipped until Bug: %s is resolved." % kwargs["bug"]
                 raise testtools.TestCase.skipException(msg)
             return f(self, *func_args, **func_kwargs)