diff --git a/doc/SETUP.org b/doc/SETUP.org
index 8ac9265..4a49dd8 100644
--- a/doc/SETUP.org
+++ b/doc/SETUP.org
@@ -59,6 +59,16 @@ This is less convenient, but gives you more control.
 
 The benefit of this way is that you get a bit more control, explicitly allowing your scripts to use your data.
 
+** optional packages
+You can also install some opional packages
+
+: pip3 install 'HPI[optional]'
+
+They aren't necessary, but improve your experience. At the moment these are:
+
+- [[https://github.com/karlicoss/cachew][cachew]]: automatic caching library, which can greatly speedup data access
+- [[https://github.com/metachris/logzero][logzero]]: a nice logging library, supporting colors
+
 * Setting up the modules
 This is an *optional step* as some modules might work without extra setup.
 But it depends on the specific module.
diff --git a/lint b/lint
index b126cfb..8061578 100755
--- a/lint
+++ b/lint
@@ -60,12 +60,20 @@ def pylint():
 
 
 def mypy(thing: str):
+    my_config_stub = DIR / 'mycfg_template'; assert my_config_stub.is_dir(), my_config_stub
+    env = {**os.environ}
+    MP = 'MYPYPATH'
+    if CI: # patch up, because CI doesn't have config... meh, but does the trick for now
+        mypypath = env.get(MP, None)
+        mypypath = str(my_config_stub) + ('' if mypypath is None else ':' + str(mypypath))
+        env[MP] = mypypath
+
     is_package = Path(thing).suffix != '.py'
     return run([
         'mypy',
         '--color-output', # TODO eh? doesn't work..
         *(['-p'] if is_package else []), thing,
-    ], stdout=PIPE, stderr=PIPE)
+    ], stdout=PIPE, stderr=PIPE, env=env)
 
 
 def mypy_all() -> Iterable[Exception]:
diff --git a/mypy.ini b/mypy.ini
index b08156c..15f1976 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -1,4 +1,5 @@
 [mypy]
+# TODO ugh. I might need to set it dynamically because of macos??
 mypy_path=~/.config/my
 pretty = True
 show_error_context = True
diff --git a/setup.py b/setup.py
index d22559b..5672e05 100644
--- a/setup.py
+++ b/setup.py
@@ -51,6 +51,11 @@ def main():
                 'pylint',
                 'mypy',
             ],
+            'optional': [
+                # TODO document these?
+                'logzero',
+                'cachew',
+            ]
         },
     )
 
diff --git a/tox.ini b/tox.ini
index 037e85c..8188028 100644
--- a/tox.ini
+++ b/tox.ini
@@ -30,7 +30,7 @@ commands = ./demo.py
 [testenv:mypy]
 skip_install = true
 commands =
-    pip install -e .[testing]
+    pip install -e .[testing] .[optional]
     ./lint