diff --git a/htdocs/comm/action/peruser.php b/htdocs/comm/action/peruser.php
index 9e2a7278a27..65669625398 100644
--- a/htdocs/comm/action/peruser.php
+++ b/htdocs/comm/action/peruser.php
@@ -1189,8 +1189,8 @@ function show_day_events2($username, $day, $month, $year, $monthshown, $style, &
 		}
 
 		$ids1='';$ids2='';
-		if (count($cases1[$h]) && array_keys($cases1[$h])) $ids1=join(',',array_keys($cases1[$h]));
-		if (count($cases2[$h]) && array_keys($cases2[$h])) $ids2=join(',',array_keys($cases2[$h]));
+		if (is_array($cases1[$h]) && count($cases1[$h]) && array_keys($cases1[$h])) $ids1=join(',',array_keys($cases1[$h]));
+		if (is_array($cases2[$h]) && count($cases2[$h]) && array_keys($cases2[$h])) $ids2=join(',',array_keys($cases2[$h]));
 
 		if ($h == $begin_h) echo '<td class="'.$style.'_peruserleft cal_peruser'.($var?' cal_impair '.$style.'_impair':'').'">';
 		else echo '<td class="'.$style.' cal_peruser'.($var?' cal_impair '.$style.'_impair':'').'">';