Index: install.php
===================================================================
RCS file: /cvs/drupal/drupal/install.php,v
retrieving revision 1.36
diff -u -r1.36 install.php
--- install.php	29 Jan 2007 12:34:29 -0000	1.36
+++ install.php	7 Feb 2007 07:32:14 -0000
@@ -316,8 +316,8 @@
   }
 
   // Verify the table prefix
-  if (!empty($db_prefix) && is_string($db_prefix) && !preg_match('/^[A-Za-z0-9_.]+$/', $db_prefix)) {
-    form_set_error('db_prefix', st('The database table prefix you have entered, %db_prefix, is invalid. The table prefix can only contain alphanumeric characters, underscores or dots.', array('%db_prefix' => $db_prefix)), 'error');
+  if (!empty($db_prefix) && is_string($db_prefix) && !preg_match('/^[A-Za-z][A-Za-z0-9_]{0,15}$/', $db_prefix)) {
+    form_set_error('db_prefix', st('The database table prefix you have entered, %db_prefix, is invalid. The table prefix can only contain alphanumeric characters and underscores.', array('%db_prefix' => $db_prefix)), 'error');
   }
 
   if (!empty($db_port) && !is_numeric($db_port)) {