diff --git a/fail2ban/server/filter.py b/fail2ban/server/filter.py
index 4bbf7996..59d2e0d7 100644
--- a/fail2ban/server/filter.py
+++ b/fail2ban/server/filter.py
@@ -343,19 +343,11 @@ class Filter(JailThread):
 		# An empty string is always false
 		if ipstr == "":
 			return
-		s = ipstr.split('/', 1)
-		# IP address without CIDR mask
-		if len(s) == 1:
-			s.insert(1, -1) # <0 means no CIDR
-		elif "." in s[1]: # 255.255.255.0 style mask
-			s[1] = IPAddr.masktoplen(s[1])
-		s[1] = long(s[1])
-		
 		# Create IP address object
-		ip = IPAddr(s[0], s[1])
+		ip = IPAddr(ipstr)
 
 		# log and append to ignore list
-		logSys.debug("Add %r to ignore list (%r, %r)", ip, s[0], s[1])
+		logSys.debug("Add %r to ignore list (%r)", ip, ipstr)
 		self.__ignoreIpList.append(ip)
 
 	def delIgnoreIP(self, ip):
diff --git a/fail2ban/server/ipdns.py b/fail2ban/server/ipdns.py
index cd22172a..8021b1d8 100644
--- a/fail2ban/server/ipdns.py
+++ b/fail2ban/server/ipdns.py
@@ -150,8 +150,20 @@ class IPAddr(object):
 		IPAddr.CACHE_OBJ.set(args, ip)
 		return ip
 
-	# object methods
-	def __init(self, ipstring, cidr=-1):
+	@staticmethod
+	def __wrap_ipstr(ipstr):
+		if "/" not in ipstr:
+			return ipstr, -1
+		s = ipstr.split('/', 1)
+		# IP address without CIDR mask
+		if len(s) > 2:
+			raise ValueError("invalid ipstr %r, too many plen representation" % (ipstr,))
+		if "." in s[1]: # 255.255.255.0 style mask
+			s[1] = IPAddr.masktoplen(s[1])
+		s[1] = long(s[1])
+		return s
+		
+	def __init(self, ipstr, cidr=-1):
 		""" initialize IP object by converting IP address string
 			to binary to integer
 		"""
@@ -160,9 +172,13 @@ class IPAddr(object):
 		self._plen = 0
 		self._maskplen = None
 		self._raw = ""
+
+		if cidr == -1:
+			ipstr, cidr = self.__wrap_ipstr(ipstr)
+
 		for family in [socket.AF_INET, socket.AF_INET6]:
 			try:
-				binary = socket.inet_pton(family, ipstring)
+				binary = socket.inet_pton(family, ipstr)
 				self._family = family
 				break
 			except socket.error:
@@ -200,18 +216,13 @@ class IPAddr(object):
 			# string couldn't be converted neither to a IPv4 nor
 			# to a IPv6 address - retain raw input for later use
 			# (e.g. DNS resolution)
-			self._raw = ipstring
+			self._raw = ipstr
 
 	def __repr__(self):
-		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
+		return self.ntoa
 
 	def __str__(self):
-		return self.__repr__()
+		return self.ntoa
 	
 	@property
 	def addr(self):
@@ -280,10 +291,10 @@ class IPAddr(object):
 	def hexdump(self):
 		"""Hex representation of the IP address (for debug purposes)
 		"""
-		if self.family == socket.AF_INET:
-			return "%08x" % self.addr
-		elif self.family == socket.AF_INET6:
-			return "%032x" % self.addr
+		if self._family == socket.AF_INET:
+			return "%08x" % self._addr
+		elif self._family == socket.AF_INET6:
+			return "%032x" % self._addr
 		else:
 			return ""
 
@@ -293,18 +304,23 @@ class IPAddr(object):
 		""" represent IP object as text like the deprecated
 			C pendant inet.ntoa but address family independent
 		"""
+		add = ''
 		if self.isIPv4:
 			# convert network to host byte order
 			binary = struct.pack("!L", self._addr)
+			if self._plen and self._plen < 32:
+				add = "/%d" % self._plen
 		elif self.isIPv6:
 			# convert network to host byte order
-			hi = self.addr >> 64
-			lo = self.addr & 0xFFFFFFFFFFFFFFFFL
+			hi = self._addr >> 64
+			lo = self._addr & 0xFFFFFFFFFFFFFFFFL
 			binary = struct.pack("!QQ", hi, lo)
+			if self._plen and self._plen < 128:
+				add = "/%d" % self._plen
 		else:
 			return self._raw
-
-		return socket.inet_ntop(self.family, binary)
+		
+		return socket.inet_ntop(self._family, binary) + add
 
 	def getPTR(self, suffix=""):
 		""" return the DNS PTR string of the provided IP address object
diff --git a/fail2ban/tests/filtertestcase.py b/fail2ban/tests/filtertestcase.py
index 44e06067..2d82ab6f 100644
--- a/fail2ban/tests/filtertestcase.py
+++ b/fail2ban/tests/filtertestcase.py
@@ -1446,6 +1446,17 @@ class DNSUtilsNetworkTests(unittest.TestCase):
 		# compare with string direct:
 		self.assertEqual(d, d2)
 
+	def testIPAddr_CIDR(self):
+		self.assertEqual(str(IPAddr('93.184.0.1', 24)), '93.184.0.0/24')
+		self.assertEqual(str(IPAddr('192.168.1.0/255.255.255.128')), '192.168.1.0/25')
+		self.assertEqual(IPAddr('93.184.0.1', 24).ntoa, '93.184.0.0/24')
+		self.assertEqual(IPAddr('192.168.1.0/255.255.255.128').ntoa, '192.168.1.0/25')
+
+		self.assertEqual(str(IPAddr('2606:2800:220:1:248:1893:25c8::', 120)), '2606:2800:220:1:248:1893:25c8:0/120')
+		self.assertEqual(IPAddr('2606:2800:220:1:248:1893:25c8::', 120).ntoa, '2606:2800:220:1:248:1893:25c8:0/120')
+		self.assertEqual(str(IPAddr('2606:2800:220:1:248:1893:25c8:0/120')), '2606:2800:220:1:248:1893:25c8:0/120')
+		self.assertEqual(IPAddr('2606:2800:220:1:248:1893:25c8:0/120').ntoa, '2606:2800:220:1:248:1893:25c8:0/120')
+
 	def testIPAddr_CompareDNS(self):
 		ips = IPAddr('example.com')
 		self.assertTrue(IPAddr("93.184.216.34").isInNet(ips))