diff --git a/da_detector.py b/da_detector.py
index ac0564f..ff58c77 100755
--- a/da_detector.py
+++ b/da_detector.py
@@ -6,7 +6,7 @@ that learns from predefined, frequency-analysed sets of ngrams
 
 
 class da_detector:
-	def __init__(self, langs_to_check=["sk", "en"]):
+	def __init__(self, langs_to_check: list = ["sk", "en"]):
 		# langs to check
 		# to be picked from ["cz", "sk", "de", "en", "fr"]
 		self.langs_to_check = langs_to_check