diff --git a/webservice/externallib.php b/webservice/externallib.php
index c9d1ab5ec2e..6eb7891aeb8 100644
--- a/webservice/externallib.php
+++ b/webservice/externallib.php
@@ -156,8 +156,8 @@ class core_webservice_external extends external_api {
 
         $siteinfo['functions'] = $availablefunctions;
 
-        // Mobile CSS theme and alternative login url
-        $siteinfo['mobilecssurl'] = get_config('admin', 'mobilecssurl');
+        // Mobile CSS theme and alternative login url.
+        $siteinfo['mobilecssurl'] = get_config(null, 'mobilecssurl');
 
         return $siteinfo;
     }
diff --git a/webservice/tests/externallib_test.php b/webservice/tests/externallib_test.php
index 93b550e0a37..75dbd9912c3 100644
--- a/webservice/tests/externallib_test.php
+++ b/webservice/tests/externallib_test.php
@@ -92,7 +92,7 @@ class core_webservice_external_testcase extends externallib_advanced_testcase {
         $this->assertEquals(true, $siteinfo['downloadfiles']);
         $this->assertEquals($CFG->release, $siteinfo['release']);
         $this->assertEquals($CFG->version, $siteinfo['version']);
-        $this->assertEquals(get_config('admin', 'mobilecssurl'), $siteinfo['mobilecssurl']);
+        $this->assertEquals(get_config(null, 'mobilecssurl'), $siteinfo['mobilecssurl']);
         $this->assertEquals(count($siteinfo['functions']), 1);
         $function = array_pop($siteinfo['functions']);
         $this->assertEquals($function['name'], 'core_course_get_contents');