diff --git a/pygam/pygam.py b/pygam/pygam.py
index 6f86ae43..ceab3ef1 100644
--- a/pygam/pygam.py
+++ b/pygam/pygam.py
@@ -8,6 +8,7 @@
 import scipy as sp
 from progressbar import ProgressBar
 from scipy import stats  # noqa: F401
+from sklearn.base import BaseEstimator
 
 from pygam.callbacks import (
     CALLBACKS,  # noqa: F401
@@ -88,7 +89,7 @@
 EPS = np.finfo(np.float64).eps  # machine epsilon
 
 
-class GAM(Core, MetaTermMixin):
+class GAM(Core, MetaTermMixin, BaseEstimator):
     """Generalized Additive Model.
 
     Parameters
@@ -3046,7 +3047,7 @@ def gridsearch(
         )
 
 
-class GammaGAM(GAM):
+
     """Gamma GAM.
 
     This is a GAM with a Gamma error distribution, and a log link.
diff --git a/pygam/tests/test_core.py b/pygam/tests/test_core.py
index b3ce7537..86f7a851 100644
--- a/pygam/tests/test_core.py
+++ b/pygam/tests/test_core.py
@@ -1,3 +1,13 @@
+"""
+Unit tests for pygam.core module.
+
+This file contains tests for the Core class and the nice_repr utility function,
+verifying that class attributes are set correctly and that the nice_repr function
+produces expected string representations.
+
+These tests help prevent regressions in the core utilities of pyGAM.
+"""
+
 from pygam.core import Core, nice_repr