diff --git a/my/__main__.py b/my/__main__.py
index 4c6ac87..b465669 100644
--- a/my/__main__.py
+++ b/my/__main__.py
@@ -1,4 +1,5 @@
 import os
+from pathlib import Path
 import sys
 from subprocess import check_call, run, PIPE
 import traceback
@@ -12,6 +13,31 @@ class Modes:
     CONFIG = 'config'
 
 
+def run_mypy(pkg):
+    from my.core.init import get_mycfg_dir
+    mycfg_dir = get_mycfg_dir()
+    # todo ugh. not sure how to extract it from pkg?
+
+    # todo dunno maybe use the same mypy config in repository?
+    # I'd need to install mypy.ini then??
+    env = {**os.environ}
+    mpath = env.get('MYPYPATH')
+    mpath = str(mycfg_dir) + ('' if mpath is None else f':{mpath}')
+    env['MYPYPATH'] = mpath
+
+    mres = run([
+        'python3', '-m', 'mypy',
+        '--namespace-packages',
+        '--color-output', # not sure if works??
+        '--pretty',
+        '--show-error-codes',
+        '--show-error-context',
+        '--check-untyped-defs',
+        '-p', pkg.__name__,
+    ], stderr=PIPE, stdout=PIPE, env=env)
+    return mres
+
+
 def config_check(args):
     def eprint(x: str):
         print(x, file=sys.stderr)
@@ -43,19 +69,7 @@ def config_check(args):
     except ImportError:
         warning("mypy not found, can't check config with it")
     else:
-        # todo dunno maybe use the same mypy config in repository?
-        # I'd need to install mypy.ini then??
-        # todo how to bring it into mypypath? cooperate with core, maybe?
-        mres = run([
-            'python3', '-m', 'mypy',
-            '--namespace-packages',
-            '--color-output', # not sure if works??
-            '--pretty',
-            '--show-error-codes',
-            '--show-error-context',
-            '--check-untyped-defs',
-            '-p', 'my.config'
-        ], stderr=PIPE, stdout=PIPE)
+        mres = run_mypy(cfg)
         rc = mres.returncode
         if rc == 0:
             info('mypy check: success')
diff --git a/my/core/init.py b/my/core/init.py
index dd21a0a..d2c7195 100644
--- a/my/core/init.py
+++ b/my/core/init.py
@@ -23,15 +23,11 @@ def assign_module(parent: str, name: str, module: ModuleType) -> None:
 
 del ModuleType
 
-# separate function to present namespace pollution
-def setup_config() -> None:
-    from pathlib import Path
-    import sys
-    import os
-    import warnings
-    from typing import Optional
-    import appdirs # type: ignore[import]
 
+def get_mycfg_dir():
+    import appdirs # type: ignore[import]
+    from pathlib import Path
+    import os
     # not sure if that's necessary, i.e. could rely on PYTHONPATH instead
     # on the other hand, by using MY_CONFIG we are guaranteed to load it from the desired path?
     mvar = os.environ.get('MY_CONFIG')
@@ -39,6 +35,16 @@ def setup_config() -> None:
         mycfg_dir = Path(mvar)
     else:
         mycfg_dir = Path(appdirs.user_config_dir('my'))
+    return mycfg_dir
+
+
+# separate function to present namespace pollution
+def setup_config() -> None:
+    import sys
+    import warnings
+    from typing import Optional
+
+    mycfg_dir = get_mycfg_dir()
 
     if not mycfg_dir.exists():
         warnings.warn(f"""