diff --git a/inc/DAVPrincipal.php b/inc/DAVPrincipal.php
index 661e5d8a..36b57b59 100644
--- a/inc/DAVPrincipal.php
+++ b/inc/DAVPrincipal.php
@@ -501,6 +501,10 @@ class DAVPrincipal extends Principal
 
       case 'http://calendarserver.org/ns/:group-membership':
       case 'DAV::group-membership':
+        if ( $request->IsProxyRequest() ) {
+          /* the calendar-proxy-{read,write} pseudo-principal should not be a member of any group */
+          return false;
+        }
         $reply->DAVElement( $prop, 'group-membership', $reply->href($this->GroupMembership()) );
         break;
 
diff --git a/testing/tests/regression-suite/0525-iCal-PROPFIND.result b/testing/tests/regression-suite/0525-iCal-PROPFIND.result
index ee40da1b..103af53e 100644
--- a/testing/tests/regression-suite/0525-iCal-PROPFIND.result
+++ b/testing/tests/regression-suite/0525-iCal-PROPFIND.result
@@ -2,8 +2,8 @@ HTTP/1.1 207 Multi-Status
 Date: Dow, 01 Jan 2000 00:00:00 GMT
 DAV: 1, 2, 3, access-control, calendar-access, calendar-schedule
 DAV: extended-mkcol, bind, addressbook, calendar-auto-schedule, calendar-proxy
-ETag: "5712eb30f86b6a9755a688c43b4bb763"
-Content-Length: 1477
+ETag: "5379cc33938a9b800403f94bdfec0571"
+Content-Length: 1091
 Content-Type: text/xml; charset="utf-8"
 
 <?xml version="1.0" encoding="utf-8" ?>
@@ -23,15 +23,6 @@ Content-Type: text/xml; charset="utf-8"
      <href>/caldav.php/user1/</href>
      <href>/caldav.php/assistant1/</href>
     </group-member-set>
-    <group-membership>
-     <href>/caldav.php/assistant1/</href>
-     <href>/caldav.php/teamclient1/</href>
-     <href>/caldav.php/user1/</href>
-     <href>/caldav.php/user1/calendar-proxy-read/</href>
-     <href>/caldav.php/assistant1/calendar-proxy-read/</href>
-     <href>/caldav.php/resource1/calendar-proxy-read/</href>
-     <href>/caldav.php/resource2/calendar-proxy-read/</href>
-    </group-membership>
     <C:calendar-proxy-read-for>
      <href>/caldav.php/user1/</href>
      <href>/caldav.php/assistant1/</href>
@@ -45,6 +36,7 @@ Content-Type: text/xml; charset="utf-8"
   <propstat>
    <prop>
     <C1:calendar-description/>
+    <group-membership/>
    </prop>
    <status>HTTP/1.1 404 Not Found</status>
   </propstat>