diff --git a/.github/workflows/test_treegp.yaml b/.github/workflows/test_treegp.yaml
index 8c21d01..6dcfd92 100644
--- a/.github/workflows/test_treegp.yaml
+++ b/.github/workflows/test_treegp.yaml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [ 3.8, 3.9, "3.10", "3.11", "3.12" ]
+        python-version: [ 3.9, "3.10", "3.11", "3.12", "3.13" ]
 
     steps:
       - uses: actions/checkout@v2
diff --git a/treegp/kernels.py b/treegp/kernels.py
index 7960feb..888b5c1 100644
--- a/treegp/kernels.py
+++ b/treegp/kernels.py
@@ -27,6 +27,8 @@ def eval_kernel(kernel):
     kernel = sklearn.gaussian_process.kernels.RBF(1)
     """
 
+    namespace = {}
+
     def recurse_subclasses(cls):
         out = []
         for c in cls.__subclasses__():
@@ -36,17 +38,17 @@ def recurse_subclasses(cls):
 
     clses = recurse_subclasses(Kernel)
     for cls in clses:
-        module = __import__(cls.__module__, globals(), locals(), cls)
-        execstr = "{0} = module.{0}".format(cls.__name__)
-        exec(execstr, globals(), locals())
+        module = __import__(cls.__module__, globals(), namespace, [cls.__name__])
+        namespace[cls.__name__] = getattr(module, cls.__name__)
+
+    from numpy import array  # if needed in the namespace
 
-    from numpy import array  # noqa: F401
+    # Add array to the namespace if necessary
+    namespace["array"] = array
 
     try:
-        k = eval(kernel)
-    except (KeyboardInterrupt, SystemExit):
-        raise
-    except Exception as e:  # pragma: no cover
+        k = eval(kernel, namespace)
+    except Exception as e:
         raise RuntimeError(
             "Failed to evaluate kernel string {0!r}.  "
             "Original exception: {1}".format(kernel, e)