diff --git a/src/Intrinsic.c b/src/Intrinsic.c
--- a/src/Intrinsic.c
+++ b/src/Intrinsic.c
@@ -1345,21 +1345,99 @@ FillInLangSubs(Substitution subs, XtPerDisplay pd)
 }
 
 /*
- * default path used if environment variable XFILESEARCHPATH
- * is not defined.  Also substitued for %D.
- * The exact value should be documented in the implementation
- * notes for any Xt implementation.
+   Return the default search path for the function
+   XtResolvePathname to use if XFILESEARCHPATH is
+   not defined.
+
+   It returns the combination the set of values which are the 6 "stems" below,
+   prepended with "/run/current-system/profile", and $GUIX_PROFILE and
+   "$HOME/.guix-profile"
+
+   These values provide the default paths where Guix/GuixSD can expect
+   to find resources for installed packages.
  */
 static const char *
-implementation_default_path(void)
+guix_default_path(void)
 {
-#if defined(WIN32)
-    static char xfilesearchpath[] = "";
+  static const char *search_path_default_stem[] = {
+    "/lib/X11/%L/%T/%N%C%S",
+    "/lib/X11/%l/%T/%N%C%S",
+    "/lib/X11/%T/%N%C%S",
+    "/lib/X11/%L/%T/%N%S",
+    "/lib/X11/%l/%T/%N%S",
+    "/lib/X11/%T/%N%S"
+  };
+
+#define SIZEOF_STEMS  (strlen (search_path_default_stem[0])	\
+		       + strlen (search_path_default_stem[1])	\
+		       + strlen (search_path_default_stem[2])	\
+		       + strlen (search_path_default_stem[3])	\
+		       + strlen (search_path_default_stem[4])	\
+		       + strlen (search_path_default_stem[5]))
+
+
+  int i;
+  const char *current_profile = "/run/current-system/profile";
+  char *home = getenv ("HOME");
+  char *guix_profile = getenv ("GUIX_PROFILE");
+
+  size_t bytesAllocd = SIZEOF_STEMS + 1;
+
+  /* This function is evaluated multiple times and the calling
+     code assumes that it is idempotent. So we must not allow
+     (say) a changed environment variable to cause it to return
+     something different. */
+  static char *path = NULL;
+  if (path)
+    return path;
+
+  bytesAllocd += 6 * (1 + strlen (current_profile));
+
+  if (guix_profile != NULL)
+    {
+      bytesAllocd += SIZEOF_STEMS;
+      bytesAllocd += 6 * (1 + strlen (guix_profile));
+    }
 
-    return xfilesearchpath;
-#else
-    return XFILESEARCHPATHDEFAULT;
-#endif
+  if (home != NULL)
+    {
+      bytesAllocd += SIZEOF_STEMS;
+      bytesAllocd += 6 * (1 + strlen(home) + strlen ("/.guix-profile"));
+    }
+
+  path = XtMalloc(bytesAllocd);
+  if (path == NULL) _XtAllocError(NULL);
+
+  memset (path, 0, bytesAllocd);
+
+  for (i = 0 ; i < 6 ; ++i)
+    {
+      strcat (path, current_profile);
+      strcat (path, search_path_default_stem[i]);
+      strcat (path, ":");
+    }
+
+  if (guix_profile != NULL)
+    for (i = 0 ; i < 6 ; ++i)
+      {
+	strcat (path, guix_profile);
+	strcat (path, search_path_default_stem[i]);
+	strcat (path, ":");
+      }
+
+  if (home != NULL)
+    for (i = 0 ; i < 6 ; ++i)
+      {
+	strcat (path, home);
+	strcat (path, "/.guix-profile");
+	strcat (path, search_path_default_stem[i]);
+	strcat (path, ":");
+      }
+
+  /* Remove final : */
+  path[strlen(path) - 1] = '\0';
+
+  return path;
 }
 
 
@@ -1388,7 +1466,7 @@ XtResolvePathname(Display *dpy,
 {
     XtPerDisplay pd;
     static const char *defaultPath = NULL;
-    const char *impl_default = implementation_default_path();
+    const char *impl_default = guix_default_path();
     int idef_len = (int) strlen(impl_default);
     char *massagedPath;
     int bytesAllocd, bytesLeft;
sts/networking.scm?id=f73ba627abd46018da7f6f41ebd5efb99412cc54'>tests: Replace uses of deprecated 'static-networking-service'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests/ganeti.scm (%ganeti-os): Replace call to
'static-networking-service' by instantiating
STATIC-NETWORKING-SERVICE-TYPE.
* gnu/tests/networking.scm (%test-static-networking)
(%openvswitch-os, %dhcpd-os): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-12-12 23:20:49 +0100'>2021-12-12</span></td><td><a href='/guix/commit/gnu/tests/networking.scm?id=223f1b1eb3707f1d3ef91200dd616ee6c8b77db0'>services: static-networking: Change interface to mimic netlink.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/base.scm (&lt;static-networking&gt;)[interface, ip, netmask]
[gateway]: Remove.
[addresses, links, routes]: New fields.
[requirement]: Default to '(udev).
(&lt;network-address&gt;, &lt;network-link&gt;, &lt;network-route&gt;): New record types.
(ensure-no-separate-netmask, %ensure-no-separate-netmask): Remove.
(ipv6-address?, cidr-&gt;netmask, ip+netmask-&gt;cidr)
(network-set-up/hurd, network-tear-down/hurd)
(network-set-up/linux, network-tear-down/linux)
(static-networking-&gt;hurd-pfinet-options): New procedures.
(static-networking-shepherd-service): New procedure.
(static-networking-shepherd-services): Rewrite in terms of the above.
(static-networking-service): Deprecate.  Adjust to new
'static-networking' API.
(%base-services): Likewise.
* gnu/system/install.scm (%installation-services): Likewise.
* gnu/system/hurd.scm (%base-services/hurd): Likewise, and separate
'loopback' from 'networking'.
* gnu/build/hurd-boot.scm (set-hurd-device-translators): Remove
"servers/socket/2".
* gnu/tests/networking.scm (run-openvswitch-test)["networking has
started on ovs0"]: Check for 'networking instead of 'networking-ovs0,
which is no longer provided.
* doc/guix.texi (Networking Setup): Document the new interface.  Remove
documentation of 'static-networking-service'.
(Virtualization Services): Change Ganeti example to use the new
interface.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-12-12 23:20:49 +0100'>2021-12-12</span></td><td><a href='/guix/commit/gnu/tests/networking.scm?id=33c498b9ee93429adc9e444ffe90df5b158fa0df'>tests: openvswitch: Check whether ovs0 is up.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests/networking.scm (run-openvswitch-test)["ovs0 is up"]: New test.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-12-12 23:20:48 +0100'>2021-12-12</span></td><td><a href='/guix/commit/gnu/tests/networking.scm?id=72f140c25314141e98f0c02950590afe84284ca2'>tests: Add 'static-networking' test.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests/networking.scm (run-static-networking-test): New procedure.
(%test-static-networking): New variable.
</span></span></td><td>Ludovic Courtès</td></tr>