diff --git a/django/contrib/admin/media/js/admin/RelatedObjectLookups.js b/django/contrib/admin/media/js/admin/RelatedObjectLookups.js
index ca578cc..5e2b4b5 100644
--- a/django/contrib/admin/media/js/admin/RelatedObjectLookups.js
+++ b/django/contrib/admin/media/js/admin/RelatedObjectLookups.js
@@ -17,9 +17,9 @@ function showRelatedObjectLookupPopup(triggeringLink) {
     name = name.replace(/\./g, '___');
     var href;
     if (triggeringLink.href.search(/\?/) >= 0) {
-        href = triggeringLink.href + '&pop=1';
+        href = triggeringLink.href + '&_popup=1';
     } else {
-        href = triggeringLink.href + '?pop=1';
+        href = triggeringLink.href + '?_popup=1';
     }
     var win = window.open(href, name, 'height=500,width=800,resizable=yes,scrollbars=yes');
     win.focus();
diff --git a/django/contrib/admin/templates/admin/search_form.html b/django/contrib/admin/templates/admin/search_form.html
index b232aa9..26dc381 100644
--- a/django/contrib/admin/templates/admin/search_form.html
+++ b/django/contrib/admin/templates/admin/search_form.html
@@ -7,7 +7,7 @@
 <input type="text" size="40" name="{{ search_var }}" value="{{ cl.query|escape }}" id="searchbar" />
 <input type="submit" value="{% trans 'Go' %}" />
 {% if show_result_count %}
-    <span class="small quiet">{% blocktrans count cl.result_count as counter %}1 result{% plural %}{{ counter }} results{% endblocktrans %} (<a href="?{% if cl.is_popup %}pop=1{% endif %}">{% blocktrans with cl.full_result_count as full_result_count %}{{ full_result_count }} total{% endblocktrans %}</a>)</span>
+    <span class="small quiet">{% blocktrans count cl.result_count as counter %}1 result{% plural %}{{ counter }} results{% endblocktrans %} (<a href="?{% if cl.is_popup %}_popup=1{% endif %}">{% blocktrans with cl.full_result_count as full_result_count %}{{ full_result_count }} total{% endblocktrans %}</a>)</span>
 {% endif %}
 {% for pair in cl.params.items %}
     {% ifnotequal pair.0 search_var %}<input type="hidden" name="{{ pair.0|escape }}" value="{{ pair.1|escape }}"/>{% endifnotequal %}
diff --git a/django/contrib/admin/views/main.py b/django/contrib/admin/views/main.py
index 116d9d4..3b3bdd4 100644
--- a/django/contrib/admin/views/main.py
+++ b/django/contrib/admin/views/main.py
@@ -24,7 +24,7 @@ ORDER_VAR = 'o'
 ORDER_TYPE_VAR = 'ot'
 PAGE_VAR = 'p'
 SEARCH_VAR = 'q'
-IS_POPUP_VAR = 'pop'
+IS_POPUP_VAR = '_popup'
 ERROR_FLAG = 'e'
 
 # Text to display within change-list table cells if the value is blank.