diff --git a/test/completion/stdlib.py b/test/completion/stdlib.py
index 140f3dae..541e9024 100644
--- a/test/completion/stdlib.py
+++ b/test/completion/stdlib.py
@@ -108,11 +108,6 @@ for a in re.finditer('a', 'a'):
     #? int()
     a.start()
 
-#?
-re.sub('a', 'a')
-#? str() bytes()
-re.sub('a', 'a', 'f')
-
 # -----------------
 # ref
 # -----------------
diff --git a/test/test_evaluate/test_stdlib.py b/test/test_evaluate/test_stdlib.py
index b340eb2b..58898ead 100644
--- a/test/test_evaluate/test_stdlib.py
+++ b/test/test_evaluate/test_stdlib.py
@@ -78,3 +78,26 @@ def test_namedtuple_goto_definitions(Script):
 
     assert d1.get_line_code() == "class Foo(tuple):\n"
     assert d1.module_path is None
+
+
+def test_re_sub(Script, environment):
+    """
+    This whole test was taken out of completion/stdlib.py, because of the
+    version differences.
+    """
+    def run(code):
+        defs = Script(code).goto_definitions()
+        return {d.name for d in defs}
+
+    names = run("import re; re.sub('a', 'a', 'f')")
+    if environment.version_info.major == 2:
+        assert names == {'str', 'unicode'}
+    else:
+        assert names == {'str', 'bytes'}
+
+    # This param is missing because of overloading.
+    names = run("import re; re.sub('a', 'a')")
+    if environment.version_info.major == 2:
+        assert names == {'str', 'unicode'}
+    else:
+        assert names == {'str', 'bytes'}