Upgrading WordPress

For one installation on my server, when I try to upgrade the version I get this message — Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 2514495 bytes) in /home1/myID/public_html/myblog/wp-includes/http.php on line 1359

Two other installations on the same server do not have this problem. Problem has been consistent over several (alas, manual) upgrades.

Any solutions?