diff --git a/python/README.md b/python/README.md
index fec7b73..c6e9978 100644
--- a/python/README.md
+++ b/python/README.md
@@ -16,6 +16,23 @@ pyoprf offers Python bindings for the liboprf library, allowing integration of O
 pip install pyoprf
 ```
 
+If you need optional transport dependencies:
+
+- `ble` installs `ble_serial`
+- `usb` installs `pyudev`
+- `all` installs both `ble_serial` and `pyudev`
+
+```bash
+# Bluetooth support
+pip install "pyoprf[ble]"
+
+# USB support
+pip install "pyoprf[usb]"
+
+# All optional transports
+pip install "pyoprf[all]"
+```
+
 ### Installing from source
 
 ```bash
diff --git a/python/pyoprf/multiplexer.py b/python/pyoprf/multiplexer.py
index 92b8b57..46d76ac 100755
--- a/python/pyoprf/multiplexer.py
+++ b/python/pyoprf/multiplexer.py
@@ -110,6 +110,8 @@ def close(self):
 
 class BLEPeer:
     def __init__(self, name, addr, server_pk, client_sk, device="hci0", timeout=5):
+        if BLE_client is None:
+            raise ImportError("BLE support requires optional dependency 'ble_serial'. Install pyoprf with the 'ble' extra, e.g. 'pip install pyoprf[ble]'.")
         self.name = name
         self.address = addr # the MAC address of the device
         self.server_pk = server_pk
@@ -278,6 +280,8 @@ async def read_raw(self,size):
 
 class USBPeer:
     def __init__(self, name, serno, server_pk, client_sk, timeout=5):
+        if pyudev is None:
+            raise ImportError("USB support requires optional dependency 'pyudev'. Install pyoprf with the 'usb' extra, e.g. 'pip install pyoprf[usb]'.")
         self.name = name
         self.serno = serno # the serial number of the usb device
         self.server_pk = server_pk
diff --git a/python/setup.py b/python/setup.py
index 912ff1b..b5d9ecd 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -20,11 +20,12 @@ def read(fname):
        license = "LGPLv3",
        author = 'Stefan Marsiske',
        author_email = 'toprf@ctrlc.hu',
-       url = 'https://github.com/stef/liboprf/python',
+       url = 'https://github.com/stef/liboprf/tree/master/python',
        long_description=read('README.md'),
        long_description_content_type="text/markdown",
        packages=find_packages(),
-       install_requires = ("pysodium", "SecureString", "pyserial", "pyudev", "ble_serial", "pyserial-asyncio"),
+       install_requires = ("pysodium", "SecureString", "pyserial", "pyserial-asyncio"),
+       extras_require = {"ble": ("ble_serial",), "usb": ("pyudev",), "all": ("ble_serial", "pyudev")},
        classifiers = ["Development Status :: 4 - Beta",
                       "License :: OSI Approved :: GNU Lesser General Public License v3 or later (LGPLv3+)",
                       "Topic :: Security :: Cryptography",