make error - libpqdll.def No such file or directory

When running make I encounter the following error:

gcc.exe: error: libpqdll.def: No such file or directory
/home/Admin/sources/postgresql-9.5.0/src/Makefile.shlib:393: recipe for target 'libpq.dll' failed
make[3]: *** [libpq.dll] Error 1
make[3]: Leaving directory '/home/Admin/builds/postgresql-9.5.0/src/interfaces/libpq'
Makefile:17: recipe for target 'all-libpq-recurse' failed
make[2]: *** [all-libpq-recurse] Error 2
make[2]: Leaving directory '/home/Admin/builds/postgresql-9.5.0/src/interfaces'
Makefile:34: recipe for target 'all-interfaces-recurse' failed
make[1]: *** [all-interfaces-recurse] Error 2
make[1]: Leaving directory '/home/Admin/builds/postgresql-9.5.0/src'
GNUmakefile:11: recipe for target 'all-src-recurse' failed
make: *** [all-src-recurse] Error 2

But /home/Admin/builds/postgresql-9.5.0/src/interfaces/libpq does contain the file libpqdll.def

Any ideas?