diff --git a/README.md b/README.md
index 82c8b36..01fdce1 100644
--- a/README.md
+++ b/README.md
@@ -16,8 +16,7 @@ Retrieve the latest replication diff from the OSM API:
 
 ```python
 >>> from osmdiff import OSMChange
->>> o = OSMChange()
->>> o.frequency = "minute"  # the default
+>>> o = OSMChange(frequency="minute")  # minute is the default frequency
 >>> o.get_state()  # retrieve current sequence ID
 >>> o.sequence_number
 2704451
@@ -104,4 +103,4 @@ I welcome your contributions in code, documentation and suggestions for enhancem
 
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 
-If you find `osmdiff` useful, or you use it in commercial software, please consider sponsoring this project.
\ No newline at end of file
+If you find `osmdiff` useful, or you use it in commercial software, please consider sponsoring this project.
diff --git a/src/osmdiff/augmenteddiff.py b/src/osmdiff/augmenteddiff.py
index efa348d..43fbe8f 100644
--- a/src/osmdiff/augmenteddiff.py
+++ b/src/osmdiff/augmenteddiff.py
@@ -1,4 +1,4 @@
-import os
+from posixpath import join as urljoin
 from xml.etree import cElementTree
 
 import dateutil.parser
@@ -49,7 +49,7 @@ def __init__(
 
     def get_state(self):
         """Get the current state from the OSM API"""
-        state_url = os.path.join(self.base_url, "augmented_diff_status")
+        state_url = urljoin(self.base_url, "augmented_diff_status")
         if self.debug:
             print("getting state from", state_url)
         response = requests.get(state_url, timeout=5)
diff --git a/src/osmdiff/osmchange.py b/src/osmdiff/osmchange.py
index 54e32e9..d6c2783 100644
--- a/src/osmdiff/osmchange.py
+++ b/src/osmdiff/osmchange.py
@@ -1,4 +1,4 @@
-import os
+from posixpath import join as urljoin
 from gzip import GzipFile
 from xml.etree import ElementTree
 
@@ -32,7 +32,7 @@ def __init__(
 
     def get_state(self):
         """Get the current state from the OSM API"""
-        state_url = os.path.join(self.base_url, self._frequency, "state.txt")
+        state_url = urljoin(self.base_url, self._frequency, "state.txt")
         response = requests.get(state_url, timeout=5)
         if response.status_code != 200:
             return False
@@ -45,7 +45,7 @@ def get_state(self):
 
     def _build_sequence_url(self):
         seqno = str(self._sequence_number).zfill(9)
-        url = os.path.join(
+        url = urljoin(
             self.base_url,
             self._frequency,
             seqno[:3],