diff --git a/crates/polars-core/src/series/implementations/time.rs b/crates/polars-core/src/series/implementations/time.rs
index 15766cb039fe..84c4b528938c 100644
--- a/crates/polars-core/src/series/implementations/time.rs
+++ b/crates/polars-core/src/series/implementations/time.rs
@@ -156,7 +156,7 @@ impl SeriesTrait for SeriesWrap<TimeChunked> {
     }
     fn split_at(&self, offset: i64) -> (Series, Series) {
         let (a, b) = self.0.split_at(offset);
-        (a.into_series(), b.into_series())
+        (a.into_time().into_series(), b.into_time().into_series())
     }
 
     fn _sum_as_f64(&self) -> f64 {
diff --git a/py-polars/polars/testing/parametric/strategies/core.py b/py-polars/polars/testing/parametric/strategies/core.py
index da412a72399d..c0cc732d71b0 100644
--- a/py-polars/polars/testing/parametric/strategies/core.py
+++ b/py-polars/polars/testing/parametric/strategies/core.py
@@ -231,10 +231,13 @@ def series(
             )
         )
 
+    print(values)
+    print(dtype)
     s = Series(name=name, values=values, dtype=dtype)
 
     # Apply masking out of values
     if do_mask_out:
+        print("hi")
         values = draw(
             st.lists(
                 st.booleans(),
@@ -249,6 +252,7 @@ def series(
 
     # Apply chunking
     if allow_chunks and size > 1 and draw(st.booleans()):
+        print("hi2")
         split_at = size // 2
         s = s[:split_at].append(s[split_at:])
 
diff --git a/py-polars/tests/unit/operations/test_merge_sorted.py b/py-polars/tests/unit/operations/test_merge_sorted.py
index 34b22d83cbdb..eb5b2420ceb9 100644
--- a/py-polars/tests/unit/operations/test_merge_sorted.py
+++ b/py-polars/tests/unit/operations/test_merge_sorted.py
@@ -1,3 +1,5 @@
+from datetime import time
+
 import pytest
 from hypothesis import given
 
@@ -58,6 +60,7 @@ def test_merge_sorted_decimal_20990(precision: int) -> None:
     assert_series_equal(result, expected)
 
 
+@pytest.mark.may_fail_auto_streaming
 def test_merge_sorted_categorical() -> None:
     left = pl.Series("a", ["a", "b"], pl.Categorical()).sort().to_frame()
     right = pl.Series("a", ["a", "b", "b"], pl.Categorical()).sort().to_frame()
@@ -139,6 +142,9 @@ def test_merge_sorted_parametric(lhs: pl.Series, rhs: pl.Series) -> None:
         excluded_dtypes=[
             pl.Struct,  # Bug. See https://github.com/pola-rs/polars/issues/20986
             pl.Binary,  # Bug. See https://github.com/pola-rs/polars/issues/20988
+            pl.Categorical(
+                ordering="lexical"
+            ),  # Bug. See https://github.com/pola-rs/polars/issues/21025
         ],
         allow_null=False,  # See: https://github.com/pola-rs/polars/issues/20991
     ),
@@ -150,3 +156,11 @@ def test_merge_sorted_self_parametric(s: pl.Series) -> None:
     append_sorted = s.append(s).sort()
 
     assert_series_equal(merge_sorted, append_sorted)
+
+
+# This was an encountered bug in the streaming engine, it was actually a bug
+# with split_at.
+def test_merge_time() -> None:
+    s = pl.Series("a", [time(0, 0)], pl.Time)
+    df = pl.DataFrame([s])
+    assert df.merge_sorted(df, "a").get_column("a").dtype == pl.Time()