diff --git a/changes/4495.bugfix.md b/changes/4495.bugfix.md
index e95e5badda..ff9e45e1c2 100644
--- a/changes/4495.bugfix.md
+++ b/changes/4495.bugfix.md
@@ -1 +1 @@
-Structured data types now default byte-string (`S`) and raw-bytes (`V`) fields to zero bytes. Before, an array with a raw-bytes field failed to create without an explicit fill value, and byte-string fields defaulted to `b"0"`.
+Structured data types now default string (`S`, `U`) and raw-bytes (`V`) fields to zero bytes. Before, an array with a raw-bytes field failed to create without an explicit fill value, and string fields defaulted to `"0"`.
diff --git a/tests/test_dtype/test_npy/test_structured.py b/tests/test_dtype/test_npy/test_structured.py
index e1920012b2..ac5c8701c6 100644
--- a/tests/test_dtype/test_npy/test_structured.py
+++ b/tests/test_dtype/test_npy/test_structured.py
@@ -394,10 +394,11 @@ def test_subarray_structured_dtype_raises() -> None:
         Struct.from_native_dtype(dtype)
 
 
-@pytest.mark.parametrize("field_dtype", ["S4", "V4"])
+@pytest.mark.parametrize("field_dtype", ["S4", "U4", "V4"])
 def test_default_scalar_bytes_field_is_zero(field_dtype: str) -> None:
     """
-    The default scalar of a bytes field is zero bytes, as for the same dtype outside a struct.
+    The default scalar of a string or bytes field is zero bytes, as for the same dtype outside
+    a struct.
     """
     dtype = np.dtype([("a", field_dtype), ("b", "<f4")])
     assert Struct.from_native_dtype(dtype).default_scalar().tobytes() == bytes(dtype.itemsize)