diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index cf03d2631..879ae8277 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.4.4
+    rev: v0.6.8
     hooks:
       # Run the linter.
       - id: ruff
diff --git a/plotnine/geoms/geom_path.py b/plotnine/geoms/geom_path.py
index 206f9a159..90c0c76ee 100644
--- a/plotnine/geoms/geom_path.py
+++ b/plotnine/geoms/geom_path.py
@@ -485,7 +485,7 @@ def _draw_segments(data: pd.DataFrame, ax: Axes, **params: Any):
         edgecolor=edgecolor,
         linewidth=linewidth,
         linestyle=linestyle,
-        capstyle=params.get("lineend", None),
+        capstyle=params.get("lineend"),
         zorder=params["zorder"],
         rasterized=params["raster"],
     )
diff --git a/plotnine/geoms/geom_raster.py b/plotnine/geoms/geom_raster.py
index 17f1f19ab..ac0276fea 100644
--- a/plotnine/geoms/geom_raster.py
+++ b/plotnine/geoms/geom_raster.py
@@ -104,7 +104,7 @@ def __init__(
         #    2. bool values for interpolation
         if "interpolate" in kwargs:
             kwargs["interpolation"] = kwargs.pop("interpolate")
-        if isinstance(kwargs.get("interpolation", None), bool):
+        if isinstance(kwargs.get("interpolation"), bool):
             if kwargs["interpolation"] is True:
                 kwargs["interpolation"] = "bilinear"
             else:
diff --git a/plotnine/geoms/geom_segment.py b/plotnine/geoms/geom_segment.py
index 0b0d0d5de..012d93b6b 100644
--- a/plotnine/geoms/geom_segment.py
+++ b/plotnine/geoms/geom_segment.py
@@ -82,7 +82,7 @@ def draw_group(
             edgecolor=color,
             linewidth=linewidth,
             linestyle=data["linetype"][0],
-            capstyle=params.get("lineend", None),
+            capstyle=params.get("lineend"),
             zorder=params["zorder"],
             rasterized=params["raster"],
         )
diff --git a/plotnine/geoms/geom_text.py b/plotnine/geoms/geom_text.py
index a8b9b4327..c3ce21646 100644
--- a/plotnine/geoms/geom_text.py
+++ b/plotnine/geoms/geom_text.py
@@ -175,7 +175,7 @@ def __init__(
     ):
         data, mapping = order_as_data_mapping(data, mapping)
         nudge_kwargs = {}
-        adjust_text = kwargs.get("adjust_text", None)
+        adjust_text = kwargs.get("adjust_text")
         if adjust_text is None:
             with suppress(KeyError):
                 nudge_kwargs["x"] = kwargs["nudge_x"]