diff --git a/snakemake/linting/__init__.py b/snakemake/linting/__init__.py
index 8ffdfe67b..3a1b0fc94 100644
--- a/snakemake/linting/__init__.py
+++ b/snakemake/linting/__init__.py
@@ -61,10 +61,10 @@ def lints(self):
 
 
 class Lint:
-    def __init__(self, title, body, links=[]):
+    def __init__(self, title, body, links=None):
         self.title = title
         self.body = body
-        self.links = links
+        self.links = links or []
 
     def __str__(self):
         width, _ = shutil.get_terminal_size()
diff --git a/snakemake/logging.py b/snakemake/logging.py
index 09c13a276..4602326ac 100644
--- a/snakemake/logging.py
+++ b/snakemake/logging.py
@@ -597,9 +597,12 @@ def job_error():
             self.last_msg_was_job_info = False
 
 
-def format_dict(dict_like, omit_keys=[], omit_values=[]):
+def format_dict(dict_like, omit_keys=None, omit_values=None):
     from snakemake.io import Namedlist
 
+    omit_keys = omit_keys or []
+    omit_values = omit_values or []
+
     if isinstance(dict_like, Namedlist):
         items = dict_like.items()
     elif isinstance(dict_like, dict):