diff --git a/becquerel/core/plotting.py b/becquerel/core/plotting.py
index df626e99..11a2652f 100644
--- a/becquerel/core/plotting.py
+++ b/becquerel/core/plotting.py
@@ -94,18 +94,17 @@ def xmode(self, mode):
                 self._xmode = "energy"
             else:
                 self._xmode = "channel"
+        elif mode.lower() in ("kev", "energy"):
+            if not self.spec.is_calibrated:
+                raise PlottingError(
+                    "Spectrum is not calibrated, however "
+                    "x axis was requested as energy"
+                )
+            self._xmode = "energy"
+        elif mode.lower() in ("channel", "channels", "chn", "chns"):
+            self._xmode = "channel"
         else:
-            if mode.lower() in ("kev", "energy"):
-                if not self.spec.is_calibrated:
-                    raise PlottingError(
-                        "Spectrum is not calibrated, however "
-                        "x axis was requested as energy"
-                    )
-                self._xmode = "energy"
-            elif mode.lower() in ("channel", "channels", "chn", "chns"):
-                self._xmode = "channel"
-            else:
-                raise PlottingError(f"Unknown x data mode: {mode}")
+            raise PlottingError(f"Unknown x data mode: {mode}")
 
         # Then, set the _xedges and _xlabel based on the _xmode
         xedges, xlabel = self.spec.parse_xmode(self._xmode)
diff --git a/becquerel/core/spectrum.py b/becquerel/core/spectrum.py
index 0ed2dde3..1e1181ff 100644
--- a/becquerel/core/spectrum.py
+++ b/becquerel/core/spectrum.py
@@ -985,13 +985,12 @@ def _mul_div(self, scaling_factor: float, div=False):
                 or np.isnan(scaling_factor)
             ):
                 raise ValueError("Scaling factor must be nonzero and finite")
-        else:
-            if (
-                scaling_factor.nominal_value == 0
-                or np.isinf(scaling_factor.nominal_value)
-                or np.isnan(scaling_factor.nominal_value)
-            ):
-                raise ValueError("Scaling factor must be nonzero and finite")
+        elif (
+            scaling_factor.nominal_value == 0
+            or np.isinf(scaling_factor.nominal_value)
+            or np.isnan(scaling_factor.nominal_value)
+        ):
+            raise ValueError("Scaling factor must be nonzero and finite")
         if div:
             multiplier = 1 / scaling_factor
         else:
@@ -1481,7 +1480,7 @@ def plot(self, *fmt, **kwargs):
         color = ax.get_lines()[-1].get_color()
         if emode == "band":
             plotter.errorband(color=color, alpha=alpha * 0.5, label="_nolegend_")
-        elif emode == "bars" or emode == "bar":
+        elif emode in ("bars", "bar"):
             plotter.errorbar(color=color, label="_nolegend_")
         elif emode != "none":
             raise SpectrumError(f"Unknown error mode '{emode}', use 'bars' or 'band'")
diff --git a/becquerel/tools/isotope.py b/becquerel/tools/isotope.py
index 3b595e60..6b041397 100644
--- a/becquerel/tools/isotope.py
+++ b/becquerel/tools/isotope.py
@@ -235,35 +235,31 @@ def _init_m(self, arg):
         if arg == "" or arg is None or arg == 0:
             self.m = ""
             self.M = 0
-        else:
-            if isinstance(arg, int):
-                if arg == 1:
-                    self.m = "m"
-                    self.M = 1
-                elif arg >= 2:
-                    self.M = arg
-                    self.m = f"m{self.M}"
-                else:
-                    raise IsotopeError(f"Metastable level must be >= 0: {arg}")
-            elif isinstance(arg, str):
-                self.m = arg.lower()
-                if self.m[0] != "m":
+        elif isinstance(arg, int):
+            if arg == 1:
+                self.m = "m"
+                self.M = 1
+            elif arg >= 2:
+                self.M = arg
+                self.m = f"m{self.M}"
+            else:
+                raise IsotopeError(f"Metastable level must be >= 0: {arg}")
+        elif isinstance(arg, str):
+            self.m = arg.lower()
+            if self.m[0] != "m":
+                raise IsotopeError(f'Metastable level must start with "m": {self.m}')
+            if len(self.m) > 1:
+                if not self.m[1:].isdigit():
                     raise IsotopeError(
-                        f'Metastable level must start with "m": {self.m}'
+                        f"Metastable level must be numeric: {self.m[0]} {self.m[1:]}"
                     )
-                if len(self.m) > 1:
-                    if not self.m[1:].isdigit():
-                        raise IsotopeError(
-                            "Metastable level must be numeric: "
-                            f"{self.m[0]} {self.m[1:]}"
-                        )
-                    self.M = int(self.m[1:])
-                else:
-                    self.M = 1
+                self.M = int(self.m[1:])
             else:
-                raise IsotopeError(
-                    f"Metastable level must be integer or string: {arg} {type(arg)}"
-                )
+                self.M = 1
+        else:
+            raise IsotopeError(
+                f"Metastable level must be integer or string: {arg} {type(arg)}"
+            )
 
     def __str__(self):
         """Define behavior of str() on Isotope."""
diff --git a/becquerel/tools/nndc.py b/becquerel/tools/nndc.py
index 570b7885..52d5f7c2 100644
--- a/becquerel/tools/nndc.py
+++ b/becquerel/tools/nndc.py
@@ -122,7 +122,7 @@ def _parse_headers(headers):
     # reformat column headers if needed
     for j, hd in enumerate(headers):
         # rename so always have T1/2 (s)
-        if hd == "T1/2 (num)" or hd == "T1/2 (seconds)":
+        if hd in ("T1/2 (num)", "T1/2 (seconds)"):
             hd = "T1/2 (s)"
         # for uncertainties, add previous column header to it
         if j > 0 and "Unc" in hd:
@@ -260,7 +260,7 @@ def _parse_float_uncertainty(x, dx):
     if "8 .0E-E5" in x:
         x = x.replace("8 .0E-E5", "8.0E-5")
     # handle blank or missing data
-    if x == "" or x == " ":
+    if x in ("", " "):
         return None
     if "****" in dx or dx in ["LT", "GT", "LE", "GE", "AP", "CA", "SY"]:
         dx = ""
diff --git a/examples/nndc_chart_of_nuclides.ipynb b/examples/nndc_chart_of_nuclides.ipynb
index 1787a409..7a31d805 100644
--- a/examples/nndc_chart_of_nuclides.ipynb
+++ b/examples/nndc_chart_of_nuclides.ipynb
@@ -17,9 +17,9 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "import matplotlib.patches as patches\n",
     "import matplotlib.pyplot as plt\n",
     "import numpy as np\n",
+    "from matplotlib import patches\n",
     "\n",
     "import becquerel as bq"
    ]
diff --git a/pyproject.toml b/pyproject.toml
index 384bc0cf..a8e69fdd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -69,7 +69,7 @@ select = [
   # "ERA",     # eradicate
   "PD",      # pandas-vet
   "PGH",     # pygrep-hooks
-  # "PL",      # pylint
+  "PL",      # pylint
   "TRY",     # tryceratops
   "FLY",     # flynt
   "NPY",     # NumPy-specific rules
@@ -87,6 +87,8 @@ ignore = [
   "SIM108",    # Use ternary operator instead of `if`-`else`-block
   "SIM300",    # Yoda conditions are discouraged
   "PD901",     # Avoid using the generic variable name `df` for DataFrames
+  "PLW2901",   # `for` loop variable overwritten by assignment target
+  "PLR2004",   # Magic value used in comparison, consider replacing with a constant variable
   "TRY003",    # Avoid specifying long messages outside the exception class
   "NPY002",    # Replace legacy `np.random.poisson` call with `np.random.Generator`
   "PERF203",   # `try`-`except` within a loop incurs performance overhead
@@ -114,7 +116,8 @@ convention = "google"
 
 [tool.ruff.lint.pylint]
 max-args = 15
-max-branches = 15
+max-branches = 60
 max-locals = 25
 max-nested-blocks = 15
-max-statements = 100
+max-returns = 20
+max-statements = 150
diff --git a/tests/materials_test.py b/tests/materials_test.py
index e595b14b..a99166a7 100644
--- a/tests/materials_test.py
+++ b/tests/materials_test.py
@@ -7,12 +7,12 @@
 import pytest
 from utils import xcom_is_up
 
-import becquerel.tools.materials as materials
-import becquerel.tools.materials_compendium as materials_compendium
 from becquerel.tools import (
     MaterialsError,
     MaterialsWarning,
     fetch_materials,
+    materials,
+    materials_compendium,
     remove_materials_csv,
 )
 from becquerel.tools.materials_nist import convert_composition
diff --git a/tests/wallet_cache_test.py b/tests/wallet_cache_test.py
index 1b4ece39..501e8c79 100644
--- a/tests/wallet_cache_test.py
+++ b/tests/wallet_cache_test.py
@@ -5,7 +5,7 @@
 import uncertainties
 from utils import nndc_is_up
 
-import becquerel.tools.wallet_cache as wallet_cache
+from becquerel.tools import wallet_cache
 
 
 @pytest.mark.parametrize(