diff --git a/keras_core/backend/common/variables.py b/keras_core/backend/common/variables.py
index 669dc3baf..21cf1d5ee 100644
--- a/keras_core/backend/common/variables.py
+++ b/keras_core/backend/common/variables.py
@@ -372,6 +372,7 @@ PYTHON_DTYPES_MAP = {
     bool: "bool",
     int: "int",  # TBD by backend
     float: "float32",
+    str: "string",
 }
 
 
diff --git a/keras_core/layers/reshaping/zero_padding3d_test.py b/keras_core/layers/reshaping/zero_padding3d_test.py
index 7b0833522..22d8b5d3d 100644
--- a/keras_core/layers/reshaping/zero_padding3d_test.py
+++ b/keras_core/layers/reshaping/zero_padding3d_test.py
@@ -65,7 +65,7 @@ class ZeroPadding3DTest(testing.TestCase, parameterized.TestCase):
             self.assertAllClose(outputs[:, 2:-2, 2:-2, 2:-2, :], inputs)
 
     @pytest.mark.skipif(
-        not backend.DYNAMIC_BATCH_SIZE_OK,
+        not backend.DYNAMIC_SHAPES_OK,
         reason="Backend does not support dynamic batch sizes",
     )
     def test_zero_padding_3d_with_dynamic_spatial_dim(self):