diff --git a/fritzbox_connection_uptime.py b/fritzbox_connection_uptime.py
index 9ad99b6..85ce0aa 100755
--- a/fritzbox_connection_uptime.py
+++ b/fritzbox_connection_uptime.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
   fritzbox_connection_uptime - A munin plugin for Linux to monitor AVM Fritzbox connection uptime
   Copyright (C) 2015 Christian Stade-Schuldt
diff --git a/fritzbox_cpu_temperature.py b/fritzbox_cpu_temperature.py
index 98346bd..fe8a9b7 100755
--- a/fritzbox_cpu_temperature.py
+++ b/fritzbox_cpu_temperature.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
   fritzbox_cpu_temperature - A munin plugin for Linux to monitor AVM Fritzbox
   Copyright (C) 2015 Christian Stade-Schuldt
diff --git a/fritzbox_cpu_usage.py b/fritzbox_cpu_usage.py
index 8230375..e108bf3 100755
--- a/fritzbox_cpu_usage.py
+++ b/fritzbox_cpu_usage.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
   fritzbox_cpu_usage - A munin plugin for Linux to monitor AVM Fritzbox
   Copyright (C) 2015 Christian Stade-Schuldt
diff --git a/fritzbox_helper.py b/fritzbox_helper.py
index f1c7829..a607541 100755
--- a/fritzbox_helper.py
+++ b/fritzbox_helper.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
   fritzbox_helper - A munin plugin for Linux to monitor AVM Fritzbox
   Copyright (C) 2015 Christian Stade-Schuldt
@@ -49,7 +49,7 @@ def get_session_id(server, username, password, port=80):
     try:
         state = get_login_state(box_url)
     except Exception as ex:
-        raise Exception("failed to get challenge") from ex
+        raise Exception("failed to get challenge")
     if state.is_pbkdf2:
         # print("PBKDF2 supported")
         challenge_response = calculate_pbkdf2_response(state.challenge, password)
diff --git a/fritzbox_memory_usage.py b/fritzbox_memory_usage.py
index 79f78d6..047131d 100755
--- a/fritzbox_memory_usage.py
+++ b/fritzbox_memory_usage.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
   fritzbox_memory_usage - A munin plugin for Linux to monitor AVM Fritzbox
   Copyright (C) 2015 Christian Stade-Schuldt
diff --git a/fritzbox_power_consumption.py b/fritzbox_power_consumption.py
index 0f4083c..fd11f68 100755
--- a/fritzbox_power_consumption.py
+++ b/fritzbox_power_consumption.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # coding=utf-8
 """
   fritzbox_power_consumption - A munin plugin for Linux to monitor AVM Fritzbox
diff --git a/fritzbox_traffic.py b/fritzbox_traffic.py
index b5a0825..bb81184 100755
--- a/fritzbox_traffic.py
+++ b/fritzbox_traffic.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
   fritzbox_traffic - A munin plugin for Linux to monitor AVM Fritzbox WAN traffic
   Copyright (C) 2015 Christian Stade-Schuldt
diff --git a/fritzbox_uptime.py b/fritzbox_uptime.py
index 204766c..5a44af4 100755
--- a/fritzbox_uptime.py
+++ b/fritzbox_uptime.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
   fritzbox_uptime - A munin plugin for Linux to monitor AVM Fritzbox
   Copyright (C) 2015 Christian Stade-Schuldt
diff --git a/fritzbox_wifi_devices.py b/fritzbox_wifi_devices.py
index 1a010ec..6c95a5b 100755
--- a/fritzbox_wifi_devices.py
+++ b/fritzbox_wifi_devices.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
   fritzbox_wifi_devices - A munin plugin for Linux to monitor AVM Fritzbox
   Copyright (C) 2015 Christian Stade-Schuldt