diff --git a/lang/en/moodle.php b/lang/en/moodle.php
index 228efc8184e..728768703fc 100644
--- a/lang/en/moodle.php
+++ b/lang/en/moodle.php
@@ -1897,6 +1897,7 @@ $string['usemessageform'] = 'or use the form below to send a message to the sele
 $string['user'] = 'User';
 $string['userconfirmed'] = 'Confirmed {$a}';
 $string['usercurrentsettings'] = 'My profile settings';
+$string['useractivity'] = 'Activity';
 $string['userdata'] = 'User data';
 $string['userdeleted'] = 'This user account has been deleted';
 $string['userdescription'] = 'Description';
diff --git a/lib/statslib.php b/lib/statslib.php
index fc457aa54ff..e77d3ec1391 100644
--- a/lib/statslib.php
+++ b/lib/statslib.php
@@ -1242,7 +1242,7 @@ function stats_get_parameters($time,$report,$courseid,$mode,$roleid=0) {
         $param->fields = 'sum(stat1+stat2) AS line1';
         $param->stattype = 'activity';
         $param->orderby = 'line1 DESC';
-        $param->line1 = get_string('activity');
+        $param->line1 = get_string('useractivity');
         $param->graphline = 'line1';
         break;
 
@@ -1268,7 +1268,7 @@ function stats_get_parameters($time,$report,$courseid,$mode,$roleid=0) {
                       ) enrolments
                       ON (activity.courseid = enrolments.courseid)
                       ORDER BY line3 DESC';
-        $param->line1 = get_string('activity');
+        $param->line1 = get_string('useractivity');
         $param->line2 = get_string('users');
         $param->line3 = get_string('activityweighted');
         $param->graphline = 'line3';