diff --git a/mayan/apps/ocr/lang/eng.py b/mayan/apps/ocr/lang/eng.py
index 53d14a0741..c402bba9f9 100644
--- a/mayan/apps/ocr/lang/eng.py
+++ b/mayan/apps/ocr/lang/eng.py
@@ -6,7 +6,7 @@ from . import BackendBase
 
 
 class LanguageBackend(BackendBase):
-    def check_word(word):
+    def check_word(self, word):
         ALL_ALPHANUM = re.compile('([0-9a-z])', re.I)
         NON_ALPHANUM = re.compile('([^0-9a-z])', re.I)
 
diff --git a/mayan/apps/ocr/lang/rus.py b/mayan/apps/ocr/lang/rus.py
index 2c56e3a38b..28b8644062 100644
--- a/mayan/apps/ocr/lang/rus.py
+++ b/mayan/apps/ocr/lang/rus.py
@@ -7,7 +7,7 @@ from . import BackendBase
 
 
 class LanguageBackend(BackendBase):
-    def check_word(word):
+    def check_word(self, word):
         ALL_ALPHANUM = re.compile('([0-9ёйцукенгшщзхъфывапролджэячсмитьбю])', re.I)
         NON_ALPHANUM = re.compile('([^0-9ёйцукенгшщзхъфывапролджэячсмитьбю])', re.I)
 
diff --git a/mayan/apps/ocr/lang/spa.py b/mayan/apps/ocr/lang/spa.py
index e0a604ec39..677aed73f6 100644
--- a/mayan/apps/ocr/lang/spa.py
+++ b/mayan/apps/ocr/lang/spa.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-záéíóúüñ])', re.I)
         NON_ALPHANUM = re.compile('([^0-9a-záéíóúüñ])', re.I)