diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 47e31884..e3e067ff 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -16,7 +16,7 @@ repos:
       # - id: end-of-file-fixer
       # - id: trailing-whitespace
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.8.6
+    rev: v0.9.4
     hooks:
       # - id: ruff
       #   args: [--fix, --exit-non-zero-on-fix]
diff --git a/doc/pylit.py b/doc/pylit.py
index 5f5a0b86..3b4397eb 100755
--- a/doc/pylit.py
+++ b/doc/pylit.py
@@ -824,7 +824,7 @@ def code_block_handler(self, block):
         for line in block:
             if line.lstrip() and self.get_indent(line) < self._codeindent:
                 raise ValueError(
-                    "code block contains line less indented " "than %d spaces \n%r" % (self._codeindent, block)
+                    "code block contains line less indented than %d spaces \n%r" % (self._codeindent, block)
                 )
             yield line.replace(" " * self._codeindent, "", 1)
 
@@ -1296,7 +1296,7 @@ def __init__(self):
         p.add_option(
             "--codeindent",
             type="int",
-            help="Number of spaces to indent code blocks with " "text2code (default %d)" % defaults.codeindent,
+            help="Number of spaces to indent code blocks with text2code (default %d)" % defaults.codeindent,
         )
 
         # Output file handling
diff --git a/refl1d/sample/flayer.py b/refl1d/sample/flayer.py
index 2f68f6ea..801006c3 100644
--- a/refl1d/sample/flayer.py
+++ b/refl1d/sample/flayer.py
@@ -167,7 +167,7 @@ def set_anchor(self, stack, index):
     # TODO: is there a sane way of computing magnetism thickness in advance?
     def _calc_thickness(self):
         if self.anchor is None:
-            raise ValueError("Need layer.magnetism.set_anchor(stack, layer) to compute" " magnetic thickness.")
+            raise ValueError("Need layer.magnetism.set_anchor(stack, layer) to compute magnetic thickness.")
         stack, index = self.anchor
         stack, start = stack._lookup(index)
         total = 0
diff --git a/refl1d/sample/layers.py b/refl1d/sample/layers.py
index 7671a2a7..49717af5 100644
--- a/refl1d/sample/layers.py
+++ b/refl1d/sample/layers.py
@@ -135,7 +135,7 @@ def __mul__(self, other):
         if not isinstance(other, int) or not other > 1:
             raise TypeError("Repeat count must be an integer > 1")
         if isinstance(self, Slab):
-            raise TypeError("Cannot repeat single slab" "")
+            raise TypeError("Cannot repeat single slab")
         stack = Stack()
         stack.add(self)
         r = Repeat(stack=stack, repeat=other)
diff --git a/refl1d/sample/material.py b/refl1d/sample/material.py
index cd81aba1..07f2b616 100644
--- a/refl1d/sample/material.py
+++ b/refl1d/sample/material.py
@@ -84,13 +84,13 @@ def __or__(self, other):
         """
         Interface for a material stacker, to support e.g., *stack = Si | air*.
         """
-        raise NotImplementedError("failed monkey-patch: material stacker needs" " to replace __or__ in Scatterer")
+        raise NotImplementedError("failed monkey-patch: material stacker needs to replace __or__ in Scatterer")
 
     def __call__(self, *args, **kw):
         """
         Interface for a material stacker, to support e.g., *stack = Si(thickness=)*.
         """
-        raise NotImplementedError("failed monkey-patch: material stacker needs" " to replace __call__ in Scatterer")
+        raise NotImplementedError("failed monkey-patch: material stacker needs to replace __call__ in Scatterer")
 
     def __str__(self):
         return self.name