diff --git a/py-polars/tests/unit/streaming/test_streaming_group_by.py b/py-polars/tests/unit/streaming/test_streaming_group_by.py
index 1e913684e95a..732c7fdf1787 100644
--- a/py-polars/tests/unit/streaming/test_streaming_group_by.py
+++ b/py-polars/tests/unit/streaming/test_streaming_group_by.py
@@ -209,16 +209,13 @@ def test_streaming_group_by_ooc_q1(
     tmp_path: Path,
     monkeypatch: Any,
 ) -> None:
-    s = random_integers
-
     tmp_path.mkdir(exist_ok=True)
     monkeypatch.setenv("POLARS_TEMP_DIR", str(tmp_path))
     monkeypatch.setenv("POLARS_FORCE_OOC", "1")
 
+    lf = random_integers.to_frame().lazy()
     result = (
-        s.to_frame()
-        .lazy()
-        .group_by("a")
+        lf.group_by("a")
         .agg(pl.first("a").alias("a_first"), pl.last("a").alias("a_last"))
         .sort("a")
         .collect(streaming=True)
@@ -240,17 +237,13 @@ def test_streaming_group_by_ooc_q2(
     tmp_path: Path,
     monkeypatch: Any,
 ) -> None:
-    s = random_integers
-
     tmp_path.mkdir(exist_ok=True)
     monkeypatch.setenv("POLARS_TEMP_DIR", str(tmp_path))
     monkeypatch.setenv("POLARS_FORCE_OOC", "1")
 
+    lf = random_integers.cast(str).to_frame().lazy()
     result = (
-        s.cast(str)
-        .to_frame()
-        .lazy()
-        .group_by("a")
+        lf.group_by("a")
         .agg(pl.first("a").alias("a_first"), pl.last("a").alias("a_last"))
         .sort("a")
         .collect(streaming=True)
@@ -266,22 +259,22 @@ def test_streaming_group_by_ooc_q2(
     assert_frame_equal(result, expected)
 
 
+@pytest.mark.skip(
+    reason="Fails randomly in the CI suite: https://github.com/pola-rs/polars/issues/13526"
+)
 @pytest.mark.write_disk()
 def test_streaming_group_by_ooc_q3(
     random_integers: pl.Series,
     tmp_path: Path,
     monkeypatch: Any,
 ) -> None:
-    s = random_integers
-
     tmp_path.mkdir(exist_ok=True)
     monkeypatch.setenv("POLARS_TEMP_DIR", str(tmp_path))
     monkeypatch.setenv("POLARS_FORCE_OOC", "1")
 
+    lf = pl.LazyFrame({"a": random_integers, "b": random_integers})
     result = (
-        pl.DataFrame({"a": s, "b": s})
-        .lazy()
-        .group_by(["a", "b"])
+        lf.group_by("a", "b")
         .agg(pl.first("a").alias("a_first"), pl.last("a").alias("a_last"))
         .sort("a")
         .collect(streaming=True)
diff --git a/py-polars/tests/unit/streaming/test_streaming_sort.py b/py-polars/tests/unit/streaming/test_streaming_sort.py
index 352b24813fa1..b4d749b1d150 100644
--- a/py-polars/tests/unit/streaming/test_streaming_sort.py
+++ b/py-polars/tests/unit/streaming/test_streaming_sort.py
@@ -92,6 +92,9 @@ def test_ooc_sort(tmp_path: Path, monkeypatch: Any) -> None:
         assert_series_equal(out, s.sort(descending=descending))
 
 
+@pytest.mark.skip(
+    reason="Fails randomly in the CI suite: https://github.com/pola-rs/polars/issues/13526"
+)
 @pytest.mark.write_disk()
 def test_streaming_sort(tmp_path: Path, monkeypatch: Any, capfd: Any) -> None:
     tmp_path.mkdir(exist_ok=True)
@@ -111,6 +114,9 @@ def test_streaming_sort(tmp_path: Path, monkeypatch: Any, capfd: Any) -> None:
     assert "df -> sort" in err
 
 
+@pytest.mark.skip(
+    reason="Fails randomly in the CI suite: https://github.com/pola-rs/polars/issues/13526"
+)
 @pytest.mark.write_disk()
 def test_out_of_core_sort_9503(tmp_path: Path, monkeypatch: Any) -> None:
     tmp_path.mkdir(exist_ok=True)
@@ -118,7 +124,7 @@ def test_out_of_core_sort_9503(tmp_path: Path, monkeypatch: Any) -> None:
     monkeypatch.setenv("POLARS_FORCE_OOC", "1")
     np.random.seed(0)
 
-    num_rows = 1_00_000
+    num_rows = 100_000
     num_columns = 2
     num_tables = 10
 
@@ -169,8 +175,7 @@ def test_out_of_core_sort_9503(tmp_path: Path, monkeypatch: Any) -> None:
 
 
 @pytest.mark.skip(
-    reason="This test is unreliable - it fails intermittently in our CI"
-    " with 'OSError: No such file or directory (os error 2)'."
+    reason="Fails randomly in the CI suite: https://github.com/pola-rs/polars/issues/13526"
 )
 @pytest.mark.write_disk()
 @pytest.mark.slow()