@@ -84,10 +84,16 @@ version of GHC.
8484
8585### `libGMP` and `libFFI`
8686
87−To build with support for `libGMP` and `libFFI` you need to pass build
88−commands for the Idris library either from the command line:
89−
90−* `stack build --flag idris:GMP --flag idris:FFI`
91−
92−or un-comment the options `idris:GMP` and `idris:FFI` and their
93−dependencies in the `stack.yaml` file.
87+By default the stack configuration in `stack.yaml` will build with
88+support for `libGMP` and `libFFI`. To turn this support off, the
89+option flags needs to be fully commented out.
90+
91+There have been reports in the past over building Idris on Mac OS X,
92+using stack, and linking to a HomeBrew installation of `libFFI`. The
93+build has failed to find the correct `libFFI` installation. If you
94+encounter this then the fix is to augment the `PKG_CONFIG_PATH` when
95+running the stack build:
96+
97+```
98+PKG_CONFIG_PATH=/usr/local/Cellar/libffi/3.0.13/lib/pkgconfig stack build
99+```