diff --git a/phpBB/install.php b/phpBB/install.php
index a48c5ab8fd..cf46049762 100644
--- a/phpBB/install.php
+++ b/phpBB/install.php
@@ -876,7 +876,7 @@ else
 					if( preg_match("/^(3\.23)|(4\.)/", $version) )
 					{
 						$sql = "ALTER TABLE " . $table_prefix . "sessions 
-							TYPE=HEAP";
+							TYPE=HEAP MAX_ROWS=500";
 						$db->sql_query($sql);
 					}
 				}
diff --git a/phpBB/upgrade.php b/phpBB/upgrade.php
index 2c25fe535f..b98178e9aa 100644
--- a/phpBB/upgrade.php
+++ b/phpBB/upgrade.php
@@ -1881,7 +1881,7 @@ if ( !empty($next) )
 			if ( preg_match("/^(3\.23)|(4\.)/", $version) )
 			{
 				$sql = "ALTER TABLE " . $table_prefix . "sessions 
-					TYPE=HEAP";
+					TYPE=HEAP MAX_ROWS=500";
 				$db->sql_query($sql);
 			}