diff --git a/flaat/issuers.py b/flaat/issuers.py
index 51594fb..8b20aa7 100644
--- a/flaat/issuers.py
+++ b/flaat/issuers.py
@@ -22,7 +22,7 @@
 def is_url(string):
     """Return True if parameter is a URL, otherwise False"""
     regex = re.compile(
-        r"^(?:http|ftp)s?://"  # http:// or https://
+        r"^(?:http|ftp)s?://"  # http:// or https://  
         r"(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?)(?:\.[A-Z]{2,6}|[A-Z0-9-]{2,})*\.?|\d{1,3}\."  # domain...
         r"localhost|"  # localhost...
         r"\d{1,3}\.\d{1,3}\.\d{1,3})"  # ...or ip