diff --git a/Course3/Lab4/validations.py b/Course3/Lab4/validations.py
index b18de65a2e..15fba0cd73 100644
--- a/Course3/Lab4/validations.py
+++ b/Course3/Lab4/validations.py
@@ -3,22 +3,29 @@
 import re
 
 def validate_user(username, minlen):
-    """Checks if the received username matches the required conditions."""
+    """Sprawdza, czy nazwa użytkownika spełnia wymagania."""
     if type(username) != str:
         raise TypeError("username must be a string")
     if minlen < 1:
         raise ValueError("minlen must be at least 1")
-    
-    # Usernames can't be shorter than minlen
+
+    # Zbyt krótka nazwa
     if len(username) < minlen:
         return False
-    # Usernames can only use letters, numbers, dots and underscores
-    if not re.match('^[a-z0-9._]*$', username):
+
+    # Nie może zaczynać się od kropki, podkreślnika ani cyfry
+    if username[0] in '._' or username[0].isnumeric():
         return False
-    # Usernames can't begin with a number
-    if username[0].isnumeric():
+
+    # Dozwolone tylko litery, cyfry, kropki i podkreślniki
+    if not re.match('^[a-zA-Z0-9._]+$', username):
         return False
-    return True
 
+    return True
 
+# TESTY
+print(validate_user("blue.kale", 3))      # True
+print(validate_user(".blue.kale", 3))     # False
+print(validate_user("red_quinoa", 4))     # True
+print(validate_user("_red_quinoa", 4))    # False