diff --git a/benchmark/benchmark.py b/benchmark/benchmark.py
index 2fd1e3a..d405f5c 100644
--- a/benchmark/benchmark.py
+++ b/benchmark/benchmark.py
@@ -75,7 +75,7 @@ def benchmark(n):
         methods = [m for m in methods if m[0].startswith("tabulate")]
 
     results = [(desc, timeit(code, setup_code, number=n) / n * 1e6) for desc, code in methods]
-    mintime = min(map(lambda x: x[1], results))
+    mintime = min(x[1] for x in results)
     results = [(desc, t, t / mintime) for desc, t in sorted(results, key=lambda x: x[1])]
     table = tabulate.tabulate(
         results, ["Table formatter", "time, μs", "rel. time"], "rst", floatfmt=".1f"
diff --git a/pyproject.toml b/pyproject.toml
index 2a80daa..11397bb 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -53,7 +53,7 @@ line-length = 99
 exclude = ["tabulate/_version.py"]
 
 [tool.ruff.lint]
-extend-select = ["W", "ISC", "I", "C90"]
+extend-select = ["W", "C4", "ISC", "I", "C90"]
 ignore = ["E721", "C901"]
 
 [tool.ruff.lint.mccabe]
diff --git a/tabulate/__init__.py b/tabulate/__init__.py
index b0810a9..38e1708 100644
--- a/tabulate/__init__.py
+++ b/tabulate/__init__.py
@@ -1592,7 +1592,7 @@ def _normalize_tabular_data(tabular_data, headers, showindex="default"):
 
     headers = list(map(str, headers))
     #    rows = list(map(list, rows))
-    rows = list(map(lambda r: r if _is_separating_line(r) else list(r), rows))
+    rows = [r if _is_separating_line(r) else list(r) for r in rows]
 
     # add or remove an index column
     showindex_is_a_str = type(showindex) in [str, bytes]
@@ -2381,7 +2381,7 @@ def tabulate(
         assert isinstance(colalign, Iterable)
         if isinstance(colalign, str):
             warnings.warn(
-                f"As a string, `colalign` is interpreted as {[c for c in colalign]}. "
+                f"As a string, `colalign` is interpreted as {list(colalign)}. "
                 f'Did you mean `colglobalalign = "{colalign}"` or `colalign = ("{colalign}",)`?',
                 stacklevel=2,
             )
@@ -2423,7 +2423,7 @@ def tabulate(
             assert isinstance(headersalign, Iterable)
             if isinstance(headersalign, str):
                 warnings.warn(
-                    f"As a string, `headersalign` is interpreted as {[c for c in headersalign]}. "
+                    f"As a string, `headersalign` is interpreted as {list(headersalign)}. "
                     f'Did you mean `headersglobalalign = "{headersalign}"` '
                     f'or `headersalign = ("{headersalign}",)`?',
                     stacklevel=2,
@@ -2702,7 +2702,7 @@ def _update_lines(self, lines, new_line):
         as add any colors from previous lines order to preserve the same formatting
         as a single unwrapped string.
         """
-        code_matches = [x for x in _ansi_codes.finditer(new_line)]
+        code_matches = list(_ansi_codes.finditer(new_line))
         color_codes = [code.string[code.span()[0] : code.span()[1]] for code in code_matches]
 
         # Add color codes from earlier in the unwrapped line, and then track any new ones we add.
diff --git a/test/common.py b/test/common.py
index b557b85..5f00852 100644
--- a/test/common.py
+++ b/test/common.py
@@ -41,6 +41,6 @@ def check_warnings(func_args_kwargs, *, num=None, category=None, contain=None):
         if num is not None:
             assert len(W) == num
         if category is not None:
-            assert all([issubclass(w.category, category) for w in W])
+            assert all(issubclass(w.category, category) for w in W)
         if contain is not None:
-            assert all([contain in str(w.message) for w in W])
+            assert all(contain in str(w.message) for w in W)
diff --git a/test/test_regression.py b/test/test_regression.py
index c23d34d..6172180 100644
--- a/test/test_regression.py
+++ b/test/test_regression.py
@@ -171,7 +171,7 @@ def test_numeric_column_headers():
     expected = "  42\n----\n   1\n   2"
     assert_equal(expected, result)
 
-    lod = [{p: i for p in range(5)} for i in range(5)]
+    lod = [dict.fromkeys(range(5), i) for i in range(5)]
     result = tabulate(lod, "keys")
     expected = "\n".join(
         [