diff --git a/tests/test_cmd.py b/tests/test_cmd.py
index 9cb69bc8..44cb928f 100644
--- a/tests/test_cmd.py
+++ b/tests/test_cmd.py
@@ -20,6 +20,21 @@ def test_c_args():
     assert [out, err] == ["['-c', '1', '2', '3']\n", ""]
 
 
+def test_reproducible_gensym():
+    out, _err = once = cmd('python -m hissp -c "(print `$#G `($#G $#G))"')
+    assert "_Qz" in out
+    again = cmd('python -m hissp -c "(print `$#G `($#G $#G))"')
+    assert once == again
+
+
+def test_unique_gensyms():
+    once, _err = cmd('python -m hissp -c "(print `$#G `($#G $#G))"')
+    assert "_Qz" in once
+    again, _err = cmd('python -m hissp -c "0 (print `$#G `($#G $#G))"')
+    assert "_Qz" in again
+    assert once != again
+
+
 def test_ic_args():
     out, err = cmd(
         'lissp -i -c "(print sys..argv)(define answer 42)" 1 2 3', "answer\n"
@@ -329,3 +344,37 @@ def test_interact_locals():
         f"! {EXIT_MSG}",
         "> #> ",
     )  # fmt: skip
+
+
+def test_subrepl():
+    call_response(
+        "> #> ", "< hissp..subrepl#sys.\n",
+        "! >>> (lambda module=__import__('sys'):\n",
+        "! ...     # hissp.._macro_.unless\n",
+        "! ...     (lambda b, a: ()if b else a())(\n",
+        "! ...       __name__==module.__name__,\n",
+        "! ...       (lambda :\n",
+        "! ...          (print(\n",
+        "! ...             'Entering',\n",
+        "! ...             module.__name__),\n",
+        "! ...           __import__('hissp').interact(\n",
+        "! ...             __import__('builtins').vars(\n",
+        "! ...               module)),\n",
+        "! ...           print(\n",
+        "! ...             'back in',\n",
+        "! ...             __name__))  [-1]\n",
+        "! ...       ))\n",
+        "! ... )()\n",
+        "> Entering sys\n",
+        f"! {BANNER}",
+        "> #> ", "< (operator..is_ (vars) (vars sys.))\n",
+        "! >>> __import__('operator').is_(\n",
+        "! ...   vars(),\n",
+        "! ...   vars(\n",
+        "! ...     __import__('sys')))\n",
+        "> True\n",
+        "> #> ",
+        f"! {EXIT_MSG}",
+        "> back in __main__\n",
+        "> #> ",
+    )  # fmt: skip
diff --git a/tests/test_reader.py b/tests/test_reader.py
index 95695697..8ebf6f59 100644
--- a/tests/test_reader.py
+++ b/tests/test_reader.py
@@ -169,6 +169,20 @@ def test_template(self):
     def test_is_string_code(self):
         self.assertFalse(reader.is_lissp_string("(1+1)"))
 
+    def test_gensym_equal(self):
+        self.assertEqual(*next(self.reader.reads(".#`($#G $#G)")))
+
+    def test_gensym_progression(self):
+        self.assertNotEqual(*self.reader.reads("`,$#G `,$#G"))
+
+    def test_gensym_name(self):
+        code = "`,$#G"
+        main = next(self.reader.reads(code))
+        name_reader = reader.Lissp(__name__, globals())
+        name = next(name_reader.reads(code))
+        self.assertNotEqual(main, name)
+        self.assertRegex(main + name, r"(?:_Qz[a-z0-7]+__G){2}")
+
 
 EXPECTED = {
     # Numeric