diff --git a/.github/linters/.ruff.toml b/.github/linters/.ruff.toml
index 9dc8ef0..ec96f28 100644
--- a/.github/linters/.ruff.toml
+++ b/.github/linters/.ruff.toml
@@ -1,7 +1,9 @@
-ignore-init-module-imports = true
 line-length = 120
 target-version = "py311"
 
+[lint]
+ignore-init-module-imports = true
+
 select = [
     "F",
     "E",
@@ -44,6 +46,7 @@ select = [
     "NPY",
     "RUF"
 ]
+
 ignore = [
     # line-too-long (handled by black)
     "E501",
@@ -91,7 +94,7 @@ ignore = [
     "TRY003",
 ]
 
-[per-file-ignores]
+[lint.per-file-ignores]
 "*test*.py" = [
     # Undocumented declarations
     "D100",
@@ -104,5 +107,5 @@ ignore = [
     "D107",
 ]
 
-[pydocstyle]
+[lint.pydocstyle]
 convention = "numpy"
diff --git a/src/safeds_runner/server/_memoization_utils.py b/src/safeds_runner/server/_memoization_utils.py
index 69963e5..eb48f59 100644
--- a/src/safeds_runner/server/_memoization_utils.py
+++ b/src/safeds_runner/server/_memoization_utils.py
@@ -10,6 +10,8 @@
 from multiprocessing.shared_memory import SharedMemory
 from typing import Any, TypeAlias
 
+import numpy as np
+
 MemoizationKey: TypeAlias = tuple[str, tuple, tuple]
 
 
@@ -201,7 +203,7 @@ def _is_not_primitive(value: Any) -> bool:
     result:
         True, if the object is not primitive.
     """
-    return not isinstance(value, str | int | float | type(None) | bool)
+    return not isinstance(value, str | int | float | type(None) | bool | np.generic)
 
 
 def _is_deterministically_hashable(value: Any) -> bool:
@@ -428,12 +430,18 @@ def _wrap_value_to_shared_memory(
         return {_wrap_value_to_shared_memory(entry) for entry in result}
     if isinstance(result, frozenset):
         return frozenset({_wrap_value_to_shared_memory(entry) for entry in result})
-    elif _is_deterministically_hashable(result):
-        _set_new_explicit_identity_deterministic_hash(result)
-        return ExplicitIdentityWrapperLazy.shared(result)
-    elif _is_not_primitive(result):
-        _set_new_explicit_identity(result)
-        return ExplicitIdentityWrapper.shared(result)
+
+    try:
+        if _is_deterministically_hashable(result):
+            _set_new_explicit_identity_deterministic_hash(result)
+            return ExplicitIdentityWrapperLazy.shared(result)
+        elif _is_not_primitive(result):
+            _set_new_explicit_identity(result)
+            return ExplicitIdentityWrapper.shared(result)
+    except AttributeError:
+        # We cannot add fields to many built-in types.
+        pass
+
     return result
 
 
diff --git a/tests/safeds_runner/server/test_memoization_utils.py b/tests/safeds_runner/server/test_memoization_utils.py
index 99bf9e0..fdf1d3c 100644
--- a/tests/safeds_runner/server/test_memoization_utils.py
+++ b/tests/safeds_runner/server/test_memoization_utils.py
@@ -1,8 +1,10 @@
 import base64
+import datetime
 import pickle
 import sys
 from typing import Any
 
+import numpy as np
 import pytest
 from safeds.data.image.containers import Image
 from safeds.data.tabular.containers import Table
@@ -308,8 +310,21 @@ def test_wrap_value_to_shared_memory_non_deterministic(value: Any) -> None:
         {"a": Table()},
         {"a", "b", Table()},
         frozenset({"a", "b", Table()}),
+        np.int64(1),
+        datetime.date(2021, 1, 1),
+    ],
+    ids=[
+        "int",
+        "list",
+        "tuple",
+        "table",
+        "tuple_table",
+        "dict",
+        "set",
+        "frozenset",
+        "numpy_int64",
+        "datetime_date",
     ],
-    ids=["int", "list", "tuple", "table", "tuple_table", "dict", "set", "frozenset"],
 )
 def test_serialize_value_to_shared_memory(value: Any) -> None:
     _wrapped = _wrap_value_to_shared_memory(value)