diff --git a/fail2ban/server/ipdns.py b/fail2ban/server/ipdns.py
index da820366..cd22172a 100644
--- a/fail2ban/server/ipdns.py
+++ b/fail2ban/server/ipdns.py
@@ -203,10 +203,15 @@ class IPAddr(object):
 			self._raw = ipstring
 
 	def __repr__(self):
-		return self.ntoa
+		if self.isIPv4 and self.plen < 32:
+			return "%s/%d" % (self.ntoa, self.plen)
+		elif self.isIPv6 and self.plen < 128:
+			return "%s/%d" % (self.ntoa, self.plen)
+		else:
+			return self.ntoa
 
 	def __str__(self):
-		return self.ntoa
+		return self.__repr__()
 	
 	@property
 	def addr(self):