diff --git a/base/univention-config-registry/python/univention/config_registry/frontend.py b/base/univention-config-registry/python/univention/config_registry/frontend.py
index d649e643ba..ec6edd66bb 100644
--- a/base/univention-config-registry/python/univention/config_registry/frontend.py
+++ b/base/univention-config-registry/python/univention/config_registry/frontend.py
@@ -330,7 +330,7 @@ def handler_filter(args, opts=dict()):
 	"""Run filter on STDIN to STDOUT."""
 	ucr = ConfigRegistry()
 	ucr.load()
-	sys.stdout.write(run_filter(sys.stdin.read(), ucr, opts=opts))
+	os.write(sys.stdout.fileno(), run_filter(sys.stdin.read(), ucr, opts=opts))
 
 
 def handler_search(args, opts=dict()):
diff --git a/base/univention-config-registry/python/univention/config_registry/handler.py b/base/univention-config-registry/python/univention/config_registry/handler.py
index 90d4e27c39..97f226518f 100644
--- a/base/univention-config-registry/python/univention/config_registry/handler.py
+++ b/base/univention-config-registry/python/univention/config_registry/handler.py
@@ -59,7 +59,7 @@ __all__ = ['ConfigHandlers']
 
 VARIABLE_PATTERN = re.compile('@%@([^@]+)@%@')
 VARIABLE_TOKEN = re.compile('@%@')
-EXECUTE_TOKEN = re.compile('@!@')
+EXECUTE_TOKEN = re.compile(b'@!@')
 WARNING_PATTERN = re.compile('(UCRWARNING|BCWARNING|UCRWARNING_ASCII)=(.+)')
 
 INFO_DIR = '/etc/univention/templates/info'
@@ -89,6 +89,8 @@ def run_filter(template, directory, srcfiles=set(), opts=dict()):
 	:param opts: UNUSED.
 	:returns: The modified template with all UCR variables and sections replaced.
 	"""
+	if isinstance(template, bytes):
+		template = template.decode('utf-8')
 	while True:
 		i = VARIABLE_TOKEN.finditer(template)
 		try:
@@ -115,6 +117,7 @@ def run_filter(template, directory, srcfiles=set(), opts=dict()):
 		except StopIteration:
 			break
 
+	template = template.encode('utf-8')
 	while True:
 		i = EXECUTE_TOKEN.finditer(template)
 		try:
@@ -124,8 +127,9 @@ def run_filter(template, directory, srcfiles=set(), opts=dict()):
 			proc = subprocess.Popen(
 				(sys.executable,),
 				stdin=subprocess.PIPE, stdout=subprocess.PIPE,
-				close_fds=True, universal_newlines=True)
-			value = proc.communicate('''\
+				close_fds=True)
+			content = template[start.end():end.start()]
+			content = b'''\
 # -*- coding: utf-8 -*-
 import univention.config_registry
 configRegistry = univention.config_registry.ConfigRegistry()
@@ -133,7 +137,8 @@ configRegistry.load()
 # for compatibility
 baseConfig = configRegistry
 %s
-''' % template[start.end():end.start()])[0]
+''' % (content,)
+			value = proc.communicate(content)[0]
 			template = template[:start.start()] + value + template[end.end():]
 
 		except StopIteration: