diff --git a/mitogen/master.py b/mitogen/master.py
index a11edb49..9eae6de5 100644
--- a/mitogen/master.py
+++ b/mitogen/master.py
@@ -523,7 +523,12 @@ class ModuleResponder(object):
         if fullname == '__main__':
             source = self.neutralize_main(source)
         compressed = zlib.compress(source)
-        related = list(self._finder.find_related(fullname))
+        related = [
+            name
+            for name in self._finder.find_related(fullname)
+            if not mitogen.core.is_blacklisted_import(self, name)
+        ]
+
         # 0:fullname 1:pkg_present 2:path 3:compressed 4:related
         tup = fullname, pkg_present, path, compressed, related
         self._cache[fullname] = tup