diff --git a/Utils.py b/Utils.py
index 202b8da1..e4e94a45 100644
--- a/Utils.py
+++ b/Utils.py
@@ -114,6 +114,8 @@ def cache_self1(function: typing.Callable[[S, T], RetType]) -> typing.Callable[[
             cache[arg] = res
             return res
 
+    wrap.__defaults__ = function.__defaults__
+
     return wrap
 
 
diff --git a/test/utils/test_caches.py b/test/utils/test_caches.py
index fc681611..b6db75c9 100644
--- a/test/utils/test_caches.py
+++ b/test/utils/test_caches.py
@@ -35,6 +35,19 @@ class TestCacheSelf1(unittest.TestCase):
         self.assertFalse(o1.func(1) is o1.func(2))
         self.assertFalse(o1.func(1) is o2.func(1))
 
+    def test_cache_default(self) -> None:
+        class Cls:
+            @cache_self1
+            def func(self, _: Any = 1) -> object:
+                return object()
+
+        o1 = Cls()
+        o2 = Cls()
+        self.assertIs(o1.func(), o1.func())
+        self.assertIs(o1.func(1), o1.func())
+        self.assertIsNot(o1.func(2), o1.func())
+        self.assertIsNot(o1.func(), o2.func())
+
     def test_gc(self) -> None:
         # verify that we don't keep a global reference
         import gc