diff --git a/README.md b/README.md
index dcca572..644571d 100644
--- a/README.md
+++ b/README.md
@@ -53,7 +53,12 @@ from requests import Response
 
 from rate_keeper import RateKeeper
 
-timestamp_clock = datetime.now(timezone.utc).timestamp
+
+# UTC timestamp clock
+def timestamp_clock():
+    return datetime.now(timezone.utc).timestamp()
+
+
 rate_keeper = RateKeeper(limit=5000, period=3600, clock=timestamp_clock)
 
 
diff --git a/README_ZH.md b/README_ZH.md
index 7ace712..a4b4608 100644
--- a/README_ZH.md
+++ b/README_ZH.md
@@ -53,7 +53,12 @@ from requests import Response
 
 from rate_keeper import RateKeeper
 
-timestamp_clock = datetime.now(timezone.utc).timestamp
+
+# UTC timestamp clock
+def timestamp_clock():
+    return datetime.now(timezone.utc).timestamp()
+
+
 rate_keeper = RateKeeper(limit=5000, period=3600, clock=timestamp_clock)
 
 
diff --git a/examples/github_api.py b/examples/github_api.py
index a7fc94a..b9da2c5 100644
--- a/examples/github_api.py
+++ b/examples/github_api.py
@@ -6,7 +6,12 @@
 
 from rate_keeper import RateKeeper
 
-timestamp_clock = datetime.now(timezone.utc).timestamp
+
+# UTC timestamp clock
+def timestamp_clock():
+    return datetime.now(timezone.utc).timestamp()
+
+
 rate_keeper = RateKeeper(limit=5000, period=3600, clock=timestamp_clock)
 
 
diff --git a/pyproject.toml b/pyproject.toml
index dc71db7..ad9dcb7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "rate-keeper"
-version = "0.4.0"
+version = "0.4.1"
 description = "Used to limit function call frequency. It ensures your function is called evenly within the limit rather than being called intensively in a short time."
 authors = [{ name = "ftnfurina", email = "ftnfurina@gmail.com" }]
 dependencies = ["requests>=2.32.3"]