pdftotext Incompatible library version

[Robin]

I am trying to use pdftotext. I have updated my ports, uninstalled and
reinstalled poppler, but get the following message:
robin-mbp:~ robince$ pdftotext
dyld: Library not loaded: /opt/local/lib/libpng12.0.dylib
  Referenced from: /opt/local/bin/pdftotext
  Reason: Incompatible library version: pdftotext requires version
45.0.0 or later, but libpng12.0.dylib provides version 40.0.0
Trace/BPT trap

I thought this usually means the dependency package (libpng) has been
rebuilt since poppler was built - but I have uninstalled and
reinstalled poppler to perform a rebuild and the problem persists.

Is there anything else I can try?

libpng is built universal:
robin-mbp:~ robince$ file /opt/local/lib/libpng12.0.dylib
/opt/local/lib/libpng12.0.dylib: Mach-O universal binary with 2 architectures
/opt/local/lib/libpng12.0.dylib (for architecture i386):        Mach-O
dynamically linked shared library i386
/opt/local/lib/libpng12.0.dylib (for architecture x86_64):      Mach-O
64-bit dynamically linked shared library x86_64

Cheers

Robin