diff --git a/chemotools/utils/banded_linalg.py b/chemotools/utils/_banded_linalg.py
similarity index 100%
rename from chemotools/utils/banded_linalg.py
rename to chemotools/utils/_banded_linalg.py
diff --git a/chemotools/utils/_whittaker_base/auto_lambda/logml.py b/chemotools/utils/_whittaker_base/auto_lambda/logml.py
index 4376daa..0c2b894 100644
--- a/chemotools/utils/_whittaker_base/auto_lambda/logml.py
+++ b/chemotools/utils/_whittaker_base/auto_lambda/logml.py
@@ -11,7 +11,7 @@
 
 import numpy as np
 
-from chemotools.utils import banded_linalg as bla
+from chemotools.utils import _banded_linalg as bla
 from chemotools.utils import models
 from chemotools.utils._whittaker_base.auto_lambda.shared import get_smooth_wrss
 
diff --git a/chemotools/utils/_whittaker_base/initialisation.py b/chemotools/utils/_whittaker_base/initialisation.py
index 8f16784..a2e3588 100644
--- a/chemotools/utils/_whittaker_base/initialisation.py
+++ b/chemotools/utils/_whittaker_base/initialisation.py
@@ -10,7 +10,7 @@
 
 import numpy as np
 
-from chemotools.utils import banded_linalg as bla
+from chemotools.utils import _banded_linalg as bla
 from chemotools.utils import finite_differences as fdiff
 from chemotools.utils import models
 from chemotools.utils.types import RealNumeric
diff --git a/chemotools/utils/_whittaker_base/main.py b/chemotools/utils/_whittaker_base/main.py
index 874cd84..91ef200 100644
--- a/chemotools/utils/_whittaker_base/main.py
+++ b/chemotools/utils/_whittaker_base/main.py
@@ -16,7 +16,7 @@
 
 from chemotools._runtime import PENTAPY_AVAILABLE
 from chemotools.utils import models
-from chemotools.utils.banded_linalg import LAndUBandCounts
+from chemotools.utils._banded_linalg import LAndUBandCounts
 from chemotools.utils._whittaker_base import auto_lambda as auto
 from chemotools.utils._whittaker_base import initialisation as init
 from chemotools.utils._whittaker_base import solvers
diff --git a/chemotools/utils/_whittaker_base/solvers.py b/chemotools/utils/_whittaker_base/solvers.py
index 01987a1..e84d26f 100644
--- a/chemotools/utils/_whittaker_base/solvers.py
+++ b/chemotools/utils/_whittaker_base/solvers.py
@@ -12,7 +12,7 @@
 import numpy as np
 
 from chemotools._runtime import PENTAPY_AVAILABLE
-from chemotools.utils import banded_linalg as bla
+from chemotools.utils import _banded_linalg as bla
 from chemotools.utils import models
 
 if PENTAPY_AVAILABLE:
diff --git a/tests/test_for_utils/test_banded_linalg.py b/tests/test_for_utils/test_banded_linalg.py
index ba40498..670c2b5 100644
--- a/tests/test_for_utils/test_banded_linalg.py
+++ b/tests/test_for_utils/test_banded_linalg.py
@@ -12,7 +12,7 @@
 import pytest
 from scipy.linalg import solve_banded as scipy_solve_banded
 
-from chemotools.utils.banded_linalg import (
+from chemotools.utils._banded_linalg import (
     _datacopied,
     conv_upper_chol_banded_to_lu_banded_storage,
     lu_banded,