Trouble with ImageMagick 6.4.1 on Mac OS X system without X11 (no decode delegate for this image format)

I have a ImageMagick 6.4.1 compiled without X11

	./configure --with-modules --without-x --without-perl --without- 
fontconfig --enable-shared

This leads to a convert program in /usr/local/bin that uses the  
following libraries:

hedwig:ImageMagick gerben$ otool -L /usr/local/bin/convert
/usr/local/bin/convert:
	/System/Library/Frameworks/ApplicationServices.framework/Versions/A/ 
ApplicationServices (compatibility version 1.0.0, current version  
34.0.0)
	/usr/local/lib/libMagickCore.1.dylib (compatibility version 2.0.0,  
current version 2.0.0)
	/usr/local/lib/libMagickWand.1.dylib (compatibility version 2.0.0,  
current version 2.0.0)
	/usr/lib/libbz2.1.0.dylib (compatibility version 1.0.0, current  
version 1.0.4)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current  
version 111.1.1)
	/usr/local/lib/libfreetype.6.dylib (compatibility version 10.0.0,  
current version 10.16.0)
	/usr/lib/libz.1.dylib (compatibility version 1.0.0, current version  
1.2.3)
	/usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current  
version 1.0.0)

On my system (where X11 is available), I can run convert

hedwig:ImageMagick gerben$ convert test.tiff test.jpg
convert: test.tiff: unknown field with tag 40961 (0xa001) encountered.  
`TIFFReadCustomDirectory'.

But when I move X11 out of the way, mimicking this stuff installed on  
a system without X11, thefollowing happens:

hedwig:ImageMagick gerben$ sudo mv /usr/X11 /usr/noX11
Password:
hedwig:ImageMagick gerben$ convert test.tiff test.jpg
convert: no decode delegate for this image format `test.tiff'.
convert: missing an image filename `test.jpg'.

That seems not correct to me. I am not a Magick development expert, I  
just compile it for others to use. Any ideas what is going on here and  
how I can fix it such that i can create a working ImageMagick on a Mac  
OS X system without X11 installed?

Thanks,

G