diff --git a/management/univention-directory-manager-modules/modules/univention/admin/syntax.py b/management/univention-directory-manager-modules/modules/univention/admin/syntax.py
index 0e7fd0d..ef8695e 100644
--- a/management/univention-directory-manager-modules/modules/univention/admin/syntax.py
+++ b/management/univention-directory-manager-modules/modules/univention/admin/syntax.py
@@ -453,7 +453,15 @@ def tostring(self, value):
 	@classmethod
 	def parse(self, text):
 		try:
-			raw = base64.b64decode(text)
+			try:
+				raw = base64.b64decode(text)
+			except (base64.binascii.Error, ValueError, TypeError):  # already binary data
+				raw = text
+				if isinstance(raw, unicode):
+					try:
+						raw = raw.encode('latin1')
+					except UnicodeEncodeError:
+						raw = raw.encode('utf-8')
 			if imghdr.what(None, raw) == 'png':
 				# convert from PNG to JPEG
 				try: