diff --git a/python/mozbuild/mozbuild/controller/clobber.py b/python/mozbuild/mozbuild/controller/clobber.py
index 34be89669628..c214762a0131 100644
--- a/python/mozbuild/mozbuild/controller/clobber.py
+++ b/python/mozbuild/mozbuild/controller/clobber.py
@@ -52,6 +52,10 @@ class Clobberer(object):
         self.src_clobber = os.path.join(topsrcdir, 'CLOBBER')
         self.obj_clobber = os.path.join(topobjdir, 'CLOBBER')
 
+        # Try looking for mozilla/CLOBBER, for comm-central
+        if not os.path.isfile(self.src_clobber):
+            self.src_clobber = os.path.join(topsrcdir, 'mozilla', 'CLOBBER')
+
         assert os.path.isfile(self.src_clobber)
 
     def clobber_needed(self):
diff --git a/testing/xpcshell/mach_commands.py b/testing/xpcshell/mach_commands.py
index 3fa9e822de98..26095b924089 100644
--- a/testing/xpcshell/mach_commands.py
+++ b/testing/xpcshell/mach_commands.py
@@ -79,6 +79,9 @@ class XPCShellRunner(MozbuildObject):
         if build_path not in sys.path:
             sys.path.append(build_path)
 
+        if not os.path.isfile(os.path.join(self.topsrcdir, 'build', 'automationutils.py')):
+            sys.path.append(os.path.join(self.topsrcdir, 'mozilla', 'build'))
+
         if test_paths == ['all']:
             self.run_suite(interactive=interactive,
                            keep_going=keep_going, shuffle=shuffle, sequential=sequential,
@@ -391,12 +394,6 @@ class B2GXPCShellRunner(MozbuildObject):
 
         return runtestsb2g.run_remote_xpcshell(parser, options, args, log)
 
-def is_platform_supported(cls):
-    """Must have a Firefox, Android or B2G build."""
-    return conditions.is_android(cls) or \
-           conditions.is_b2g(cls) or \
-           conditions.is_firefox(cls)
-
 @CommandProvider
 class MachCommands(MachCommandBase):
     def __init__(self, context):
@@ -406,7 +403,6 @@ class MachCommands(MachCommandBase):
             setattr(self, attr, getattr(context, attr, None))
 
     @Command('xpcshell-test', category='testing',
-        conditions=[is_platform_supported],
         description='Run XPCOM Shell tests (API direct unit testing)',
         parser=_parser)
     @CommandArgument('test_paths', default='all', nargs='*', metavar='TEST',