diff --git a/pylintrc b/pylintrc
new file mode 100644
index 0000000..afd255f
--- /dev/null
+++ b/pylintrc
@@ -0,0 +1,20 @@
+
+[MESSAGES CONTROL]
+
+disable=consider-using-in,
+        duplicate-code,
+        invalid-name,
+        no-else-return,
+        superfluous-parens,
+        too-few-public-methods,
+        too-many-arguments,
+        too-many-branches,
+        too-many-instance-attributes,
+        too-many-lines,
+        too-many-locals,
+        too-many-nested-blocks,
+        too-many-public-methods,
+        too-many-return-statements,
+        too-many-statements,
+        unnecessary-pass
+
diff --git a/python/run_matching.py b/python/run_matching.py
index 3be4a14..c16c330 100755
--- a/python/run_matching.py
+++ b/python/run_matching.py
@@ -73,7 +73,7 @@ def read_dimacs_graph(f: TextIO) -> list[tuple[int, int, int|float]]:
 def read_dimacs_graph_file(filename: str) -> list[tuple[int, int, int|float]]:
     """Read a graph from file or stdin."""
     if filename:
-        with open(filename, "r") as f:
+        with open(filename, "r", encoding="ascii") as f:
             try:
                 return read_dimacs_graph(f)
             except ValueError as exc:
@@ -140,7 +140,7 @@ def read_dimacs_matching_file(
         filename: str
         ) -> tuple[int|float, list[tuple[int, int]]]:
     """Read a matching from file."""
-    with open(filename, "r") as f:
+    with open(filename, "r", encoding="ascii") as f:
         try:
             return read_dimacs_matching(f)
         except ValueError as exc:
@@ -170,7 +170,7 @@ def write_dimacs_matching_file(
         ) -> None:
     """Write a matching to file or stdout."""
     if filename:
-        with open(filename, "x") as f:
+        with open(filename, "x", encoding="ascii") as f:
             write_dimacs_matching(f, weight, pairs)
     else:
         write_dimacs_matching(sys.stdout, weight, pairs)
diff --git a/tests/generate/make_slow_graph.py b/tests/generate/make_slow_graph.py
index 5899d5d..b0b2b86 100644
--- a/tests/generate/make_slow_graph.py
+++ b/tests/generate/make_slow_graph.py
@@ -19,6 +19,7 @@ count_delta_step = [0]
 
 def patch_matching_code() -> None:
     """Patch the matching code to count events."""
+    # pylint: disable=import-outside-toplevel,protected-access
 
     import mwmatching
 
@@ -44,6 +45,8 @@ def run_max_weight_matching(
         edges: list[tuple[int, int, int]]
         ) -> tuple[list[tuple[int, int]], int, int]:
     """Run the matching algorithm and count subroutine calls."""
+    # pylint: disable=import-outside-toplevel
+
     import mwmatching
 
     count_make_blossom[0] = 0
@@ -322,7 +325,7 @@ def main() -> int:
         assert False
 
     if args.check:
-        (pairs, num_blossom, num_delta) = run_max_weight_matching(edges)
+        (_pairs, num_blossom, num_delta) = run_max_weight_matching(edges)
         print(f"n={args.n} m={len(edges)} "
               f"nblossom={num_blossom} ndelta={num_delta}",
               file=sys.stderr)
diff --git a/tests/run_test.py b/tests/run_test.py
index 3e684ed..4e3de45 100755
--- a/tests/run_test.py
+++ b/tests/run_test.py
@@ -45,6 +45,7 @@ class Matching(NamedTuple):
 
 
 class RunStatus(enum.IntEnum):
+    """Result categories for running a solver."""
     OK = 0
     FAILED = 1
     WRONG_ANSWER = 2
@@ -440,7 +441,7 @@ class WmatchSolver(Solver):
                 y = int(words[1])
             except ValueError:
                 raise SolverError("Invalid format in solver output") from None
-            if x > 0 and x < y:
+            if 0 < x < y:
                 pairs.append((x - 1, y - 1))
 
         return Matching(pairs)
@@ -660,7 +661,7 @@ def test_input(
     for filename in files:
 
         try:
-            with open(filename, "r") as f:
+            with open(filename, "r", encoding="ascii") as f:
                 graph = read_dimacs_graph(f)
         except (OSError, ValueError) as exc:
             print(f"ERROR: Can not read graph {filename!r} ({exc})",
@@ -671,7 +672,7 @@ def test_input(
         if verify:
             reffile = os.path.splitext(filename)[0] + ".out"
             try:
-                with open(reffile, "r") as f:
+                with open(reffile, "r", encoding="ascii") as f:
                     (gold_weight, _matching) = read_dimacs_matching(f)
             except (OSError, ValueError) as exc:
                 print(f"ERROR: Can not read matching {reffile!r} ({exc})",