diff --git a/plugins/system/read_serial_temperature b/plugins/system/read_serial_temperature
index dd4fcf44..8329ef9e 100755
--- a/plugins/system/read_serial_temperature
+++ b/plugins/system/read_serial_temperature
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 """
 Paul Wiegmans (p.wiegmans@bonhoeffer.nl)
 2009 dec 18
@@ -12,42 +12,39 @@ Linux: "/dev/usb/ttyUSB[n]" or "/dev/ttyUSB[n]"
     e.g. "/dev/usb/ttyUSB0"
 """
 
-import sys, serial
+import sys
+
+import serial
+
 
 # Open named port at "19200,8,N,1", 1s timeout::
-
 def gettemperature():
-	ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)
-	t = 0
-	while t<1:
-		line = ser.readline().strip()
-		if line:
-			temp = str(line.split(" ")[0]) # temperature in tenths celsius
-			i = len(temp)-1
-			temp = temp[:i]  # return only integer value (as a string)
-			return temp
-			t += 1
-	ser.close()
+    connection = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)
+    # default to munin's value "unknown"
+    result = "U"
+    while True:
+        line = connection.readline().strip()
+        if line:
+            # temperature in tenths celsius
+            temp = str(line.split(" ")[0])
+            # return only integer value (as a string)
+            result = temp[:-1]
+            break
+    connection.close()
+    return result
+
 
 # shamelessly copied from weather_temp_
-
 if len(sys.argv) == 2 and sys.argv[1] == "autoconf":
-
-  print "yes"
-
+    print("yes")
 elif len(sys.argv) == 2 and sys.argv[1] == "config":
-
-  print 'graph_title Temperatuur in de serverruimte'
-  print 'graph_vlabel temperature in C'
-  print 'graph_category sensors'
-  print 'temperature.label temperature'
-  print 'graph_info Dit is de temperatuur in het rek in de serverruimte B104'
-  print 'graph_scale no'
-  # lower limit 10, upper limit 50
-  print 'graph_args --base 1000 -l 10 -u 50'
-
+    print('graph_title Temperatuur in de serverruimte')
+    print('graph_vlabel temperature in C')
+    print('graph_category sensors')
+    print('temperature.label temperature')
+    print('graph_info Dit is de temperatuur in het rek in de serverruimte B104')
+    print('graph_scale no')
+    # lower limit 10, upper limit 50
+    print('graph_args --base 1000 -l 10 -u 50')
 else:
-
-  print 'temperature.value %s' % gettemperature()
-
-
+    print('temperature.value %s' % gettemperature())
diff --git a/t/test-exception-wrapper.expected-failures b/t/test-exception-wrapper.expected-failures
index e82e1965..91a67d93 100644
--- a/t/test-exception-wrapper.expected-failures
+++ b/t/test-exception-wrapper.expected-failures
@@ -427,7 +427,6 @@ plugins/system/auth
 plugins/system/blockhosts
 plugins/systemd/systemd_units
 plugins/system/file_length_
-plugins/system/read_serial_temperature
 plugins/tarsnap/tarsnap
 plugins/tcp/tcp-retransmissions
 plugins/tcp/tcp-states