I was having a few PHP problems post-Mountain Lion upgrade. Specifically I couldn’t get any sites working that utilised mcrypt with PHP.

Executing php at the command line told me the following:

PHP Warning: PHP Startup: Unable to load dynamic library ‘/usr/local/Cellar/php53-mcrypt/5.3.13/mcrypt.so’ - dlopen(/usr/local/Cellar/php53-mcrypt/5.3.13/mcrypt.so, 9): Library not loaded: /usr/lib/libltdl.7.dylib Referenced from: /usr/local/Cellar/php53-mcrypt/5.3.13/mcrypt.so Reason: image not found in Unknown on line 0

I decided to reinstall Jose Gonzalez' convenient php53-mcrypt formula. Post install, the PHP was able to start up without error and a quick otool -L on mcrypt.sorevealed that it no longer had a dependency on libltdl.7.dylib.