diff --git a/atools/_memoize_decorator.py b/atools/_memoize_decorator.py
index ac7e47b..ffe8028 100644
--- a/atools/_memoize_decorator.py
+++ b/atools/_memoize_decorator.py
@@ -123,11 +123,14 @@ def table_name(self) -> str:
 
     def default_keygen(self, *args, **kwargs) -> Tuple[Hashable, ...]:
         """Returns all params (args, kwargs, and missing default kwargs) for function as kwargs."""
+
+        return tuple(self.get_args_as_kwargs(*args, **kwargs).values())
+
+    def get_args_as_kwargs(self, *args, **kwargs) -> Mapping[str, Any]:
         args_as_kwargs = {}
         for k, v in zip(self.default_kwargs, args):
             args_as_kwargs[k] = v
-
-        return tuple(ChainMap(args_as_kwargs, kwargs, self.default_kwargs).values())
+        return ChainMap(args_as_kwargs, kwargs, self.default_kwargs)
 
     def get_memo(self, key: Union[int, str]) -> _Memo:
         try:
@@ -221,7 +224,7 @@ async def get_key(self, *args, **kwargs) -> Union[int, str]:
         if self.keygen is None:
             key = self.default_keygen(*args, **kwargs)
         else:
-            key = self.keygen(*args, **kwargs)
+            key = self.keygen(**self.get_args_as_kwargs(*args, **kwargs))
             if isinstance(key, tuple):
                 key = list(key)
             else:
@@ -277,7 +280,7 @@ def get_key(self, *args, **kwargs) -> Union[int, str]:
         if self.keygen is None:
             key = self.default_keygen(*args, **kwargs)
         else:
-            key = self.keygen(*args, **kwargs)
+            key = self.keygen(**self.get_args_as_kwargs(*args, **kwargs))
 
         key = self.get_hashed_key(key)
 
diff --git a/setup.py b/setup.py
index ee2987c..4e6d25d 100644
--- a/setup.py
+++ b/setup.py
@@ -2,7 +2,7 @@
 
 setup(
     name='atools',
-    version='0.10.4',
+    version='0.10.5',
     packages=find_packages(),
     python_requires='>=3.6',
     url='https://github.com/cevans87/atools',
diff --git a/test/test_memoize_decorator.py b/test/test_memoize_decorator.py
index d072da2..d4cba68 100644
--- a/test/test_memoize_decorator.py
+++ b/test/test_memoize_decorator.py
@@ -919,3 +919,11 @@ def _foo() -> None:
     del foo
     # FIXME there's a race condition here. Garbage collector may not have cleaned up foo yet
     assert r() is None
+
+
+def test_keygen_works_with_default_kwargs() -> None:
+    @memoize(keygen=lambda bar: bar)
+    def foo(bar=1) -> None:
+        ...
+
+    foo()