diff --git a/htdocs/core/lib/date.lib.php b/htdocs/core/lib/date.lib.php
index ae138bcceec..a751f584564 100644
--- a/htdocs/core/lib/date.lib.php
+++ b/htdocs/core/lib/date.lib.php
@@ -912,7 +912,7 @@ function num_open_day($timestampStart, $timestampEnd, $inhour = 0, $lastday = 0,
 
 		$nbOpenDay=$lastday;
 
-		if ($inhour == 1) $nbOpenDay = $nbOpenDay*24 . $langs->trans("HourShort");
+		if ($inhour == 1) $nbOpenDay = ($nbOpenDay * 24);
 		return $nbOpenDay - (($inhour == 1 ? 12 : 0.5) * abs($halfday));
 	}
 	else