diff --git a/my/core/cachew.py b/my/core/cachew.py
index cc5a95b..bcd838d 100644
--- a/my/core/cachew.py
+++ b/my/core/cachew.py
@@ -1,4 +1,4 @@
-from .common import assert_subpackage; assert_subpackage(__name__)
+from .internal import assert_subpackage; assert_subpackage(__name__)
 
 from contextlib import contextmanager
 import logging
diff --git a/my/core/common.py b/my/core/common.py
index 32e277b..f23ffbf 100644
--- a/my/core/common.py
+++ b/my/core/common.py
@@ -173,12 +173,6 @@ def asdict(thing: Any) -> Json:
     raise TypeError(f'Could not convert object {thing} to dict')
 
 
-def assert_subpackage(name: str) -> None:
-    # can lead to some unexpected issues if you 'import cachew' which being in my/core directory.. so let's protect against it
-    # NOTE: if we use overlay, name can be smth like my.origg.my.core.cachew ...
-    assert name == '__main__' or 'my.core' in name, f'Expected module __name__ ({name}) to be __main__ or start with my.core'
-
-
 # TODO deprecate and suggest to use one from my.core directly? not sure
 from .utils.itertools import unique_everseen
 
diff --git a/my/core/freezer.py b/my/core/freezer.py
index 649a2b7..09ba032 100644
--- a/my/core/freezer.py
+++ b/my/core/freezer.py
@@ -1,4 +1,4 @@
-from .common import assert_subpackage; assert_subpackage(__name__)
+from .internal import assert_subpackage; assert_subpackage(__name__)
 
 import dataclasses as dcl
 import inspect
diff --git a/my/core/influxdb.py b/my/core/influxdb.py
index 8407264..4f0e4c4 100644
--- a/my/core/influxdb.py
+++ b/my/core/influxdb.py
@@ -1,7 +1,8 @@
 '''
 TODO doesn't really belong to 'core' morally, but can think of moving out later
 '''
-from .common import assert_subpackage; assert_subpackage(__name__)
+
+from .internal import assert_subpackage; assert_subpackage(__name__)
 
 from typing import Iterable, Any, Optional, Dict
 
diff --git a/my/core/internal.py b/my/core/internal.py
new file mode 100644
index 0000000..8b9882b
--- /dev/null
+++ b/my/core/internal.py
@@ -0,0 +1,9 @@
+"""
+Utils specific to hpi core, shouldn't really be used by HPI modules
+"""
+
+
+def assert_subpackage(name: str) -> None:
+    # can lead to some unexpected issues if you 'import cachew' which being in my/core directory.. so let's protect against it
+    # NOTE: if we use overlay, name can be smth like my.origg.my.core.cachew ...
+    assert name == '__main__' or 'my.core' in name, f'Expected module __name__ ({name}) to be __main__ or start with my.core'
diff --git a/my/core/kompress.py b/my/core/kompress.py
index 25dba8c..6ab3228 100644
--- a/my/core/kompress.py
+++ b/my/core/kompress.py
@@ -1,4 +1,4 @@
-from .common import assert_subpackage; assert_subpackage(__name__)
+from .internal import assert_subpackage; assert_subpackage(__name__)
 from . import warnings
 
 # do this later -- for now need to transition modules to avoid using kompress directly (e.g. ZipPath)
diff --git a/my/core/mime.py b/my/core/mime.py
index c8abc7e..cf5bdf5 100644
--- a/my/core/mime.py
+++ b/my/core/mime.py
@@ -2,7 +2,7 @@
 Utils for mime/filetype handling
 """
 
-from .common import assert_subpackage; assert_subpackage(__name__)
+from .internal import assert_subpackage; assert_subpackage(__name__)
 
 import functools
 
diff --git a/my/core/pytest.py b/my/core/pytest.py
index a2596fb..c73c71a 100644
--- a/my/core/pytest.py
+++ b/my/core/pytest.py
@@ -2,7 +2,7 @@
 Helpers to prevent depending on pytest in runtime
 """
 
-from .common import assert_subpackage; assert_subpackage(__name__)
+from .internal import assert_subpackage; assert_subpackage(__name__)
 
 import sys
 import typing
diff --git a/my/core/sqlite.py b/my/core/sqlite.py
index 2580e15..4a471a9 100644
--- a/my/core/sqlite.py
+++ b/my/core/sqlite.py
@@ -1,4 +1,4 @@
-from .common import assert_subpackage; assert_subpackage(__name__)
+from .internal import assert_subpackage; assert_subpackage(__name__)
 
 
 from contextlib import contextmanager