diff --git a/nsupdate/api/views.py b/nsupdate/api/views.py
index 0e3a22f..84b3517 100644
--- a/nsupdate/api/views.py
+++ b/nsupdate/api/views.py
@@ -8,6 +8,7 @@ from django.conf import settings
 from django.contrib.auth.hashers import check_password
 from django.contrib.auth.decorators import login_required
 from django.contrib.sessions.backends.db import SessionStore
+from django.utils.timezone import now
 
 from ..main.models import Host
 from ..main.dnstools import update, SameIpError, check_ip
@@ -49,6 +50,8 @@ def DetectIpView(request, secret=None):
     ipaddr = request.META['REMOTE_ADDR']
     key = check_ip(ipaddr)
     s[key] = ipaddr
+    s[key+'_timestamp'] = now()
+    logger.debug("detected %s: %s" % (key, ipaddr))
     s.save()
     return HttpResponse(status=204)
 
diff --git a/nsupdate/context_processors.py b/nsupdate/context_processors.py
index 086ffb8..390d82a 100644
--- a/nsupdate/context_processors.py
+++ b/nsupdate/context_processors.py
@@ -1,5 +1,11 @@
 # -*- coding: utf-8 -*-
+
+from datetime import timedelta
+
 from django.conf import settings
+from django.utils.timezone import now
+
+MAX_IP_AGE = 180  # seconds
 
 
 def add_settings(request):
@@ -8,3 +14,33 @@ def add_settings(request):
     context['WWW_IPV4_HOST'] = settings.WWW_IPV4_HOST
     context['WWW_IPV6_HOST'] = settings.WWW_IPV6_HOST
     return context
+
+
+def remove_stale_ips(request):
+    """
+    Check the session if there are stale IPs and if so, remove them.
+    """
+    # XXX is a context processor is the right place for this?
+    s = request.session
+    t_now = now()
+    for key in ['ipv4', 'ipv6', ]:
+        timestamp_key = "%s_timestamp" % key
+        try:
+            timestamp = s[timestamp_key]
+        except KeyError:
+            pass
+        else:
+            try:
+                stale = timestamp + timedelta(seconds=MAX_IP_AGE) < t_now
+            except (ValueError, TypeError):
+                # invalid timestamp in session
+                del s[timestamp_key]
+            else:
+                if stale:
+                    print "ts: %s now: %s - killing %s (was: %s)" % (timestamp, t_now, key, s[key])
+                    # kill the IP, it is not up-to-date any more
+                    # note: it is used to fill form fields, so set it to empty string
+                    s[key] = ''
+                    # update the timestamp, so we can retry after a while
+                    s[timestamp_key] = t_now
+    return {}
diff --git a/nsupdate/main/templates/main/overview.html b/nsupdate/main/templates/main/overview.html
index 9a5d0fc..160ba7b 100644
--- a/nsupdate/main/templates/main/overview.html
+++ b/nsupdate/main/templates/main/overview.html
@@ -36,8 +36,12 @@
         <div class="col-lg-8">
             <div class="well well-sm">
                 <h3>Your current IPs</h3>
-                <p><b>Your IPv4:</b> <span class="ipv4addr">{{ request.session.ipv4 }}</span></p>
-                <p><b>Your IPv6:</b> <span class="ipv6addr">{{ request.session.ipv6 }}</span></p>
+                {%  if request.session.ipv4 %}
+                <p><b>IPv4:</b> <span class="ipv4addr">{{ request.session.ipv4 }}</span> (seen {{request.session.ipv4_timestamp|timesince}} ago)</p>
+                {%  endif %}
+                {%  if request.session.ipv6 %}
+                <p><b>IPv6:</b> <span class="ipv6addr">{{ request.session.ipv6 }}</span> (seen {{request.session.ipv6_timestamp|timesince}} ago)</p>
+                {% endif %}
                 <p>Note: We try to get your IP addresses through a trick, by hosting two fake images:</p>
                 <ol>
                     <li>on a IPv4-only server</li>
diff --git a/nsupdate/settings.py b/nsupdate/settings.py
index bde70dc..fd403db 100644
--- a/nsupdate/settings.py
+++ b/nsupdate/settings.py
@@ -34,6 +34,10 @@ WWW_HOST = BASEDOMAIN
 WWW_IPV4_HOST = 'ipv4.' + BASEDOMAIN
 WWW_IPV6_HOST = 'ipv6.' + BASEDOMAIN
 
+# for debugging IP detection on localhost
+#WWW_IPV4_HOST = 'localhost:8000'
+#WWW_IPV6_HOST = 'ip6-localhost:8000'
+
 BAD_AGENTS = set()  # useragent blacklist for /nic/update service
 
 # Hosts/domain names that are valid for this site; required if DEBUG is False
@@ -119,6 +123,7 @@ MIDDLEWARE_CLASSES = (
 TEMPLATE_CONTEXT_PROCESSORS = DEFAULT_SETTINGS.TEMPLATE_CONTEXT_PROCESSORS + (
     'django.core.context_processors.request',
     'nsupdate.context_processors.add_settings',
+    'nsupdate.context_processors.remove_stale_ips',
 )
 
 ROOT_URLCONF = 'nsupdate.urls'
diff --git a/nsupdate/templates/base.html b/nsupdate/templates/base.html
index 9bac7b3..25b447e 100644
--- a/nsupdate/templates/base.html
+++ b/nsupdate/templates/base.html
@@ -100,15 +100,21 @@
         </div>
         <script src="//netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>
         <div style="display: none">
-            <img id="v4_img" alt="fake image used for ip v4 address detection" />
-            <img id="v6_img" alt="fake image used for ip v6 address detection" />
-            <script type="text/javascript">
-                function insert_src() {
-                    $('#v4_img').attr('src', "//{{ WWW_IPV4_HOST }}/detectip/{{ request.session.session_key }}/");
-                    $('#v6_img').attr('src', "//{{ WWW_IPV6_HOST }}/detectip/{{ request.session.session_key }}/");
-                };
-                $(setTimeout("insert_src()", 1000));
-            </script>
+            {% if not request.session.ipv4 %}
+                <img id="v4_img" alt="fake image used for ip v4 address detection" />
+            {% endif %}
+            {% if not request.session.ipv6 %}
+                <img id="v6_img" alt="fake image used for ip v6 address detection" />
+            {% endif %}
+            {% if not request.session.ipv4 or not request.session.ipv6 %}
+                <script type="text/javascript">
+                    function insert_src() {
+                        $('#v4_img').attr('src', "//{{ WWW_IPV4_HOST }}/detectip/{{ request.session.session_key }}/");
+                        $('#v6_img').attr('src', "//{{ WWW_IPV6_HOST }}/detectip/{{ request.session.session_key }}/");
+                    };
+                    $(setTimeout("insert_src()", 1000));
+                </script>
+            {% endif %}
         </div>
     </body>
 </html>