diff --git a/mayan/apps/ocr/lang/deu.py b/mayan/apps/ocr/lang/deu.py
index df20573b09..6291843844 100644
--- a/mayan/apps/ocr/lang/deu.py
+++ b/mayan/apps/ocr/lang/deu.py
@@ -7,7 +7,7 @@ from . import BackendBase
 
 
 class LanguageBackend(BackendBase):
-    def check_word(word):
+    def check_word(self, word):
         ALL_ALPHANUM = re.compile('([0-9a-zäöüß])', re.I)
         NON_ALPHANUM = re.compile('([^0-9a-zäöüß])', re.I)
         ALL_ALPHANUM = re.compile('([0-9a-z])', re.I)