Segfault on Ubuntu 14.04

[refi64]

When running the demo app, the outline of a window appears, then it crashes. This is the gdb backtrace:

#0  0x00007ffff556af66 in __readdir (dirp=0x0) at ../sysdeps/posix/readdir.c:44
#1  0x00007ffff7a626b9 in mk::spritesInFolder(NVGcontext*, mk::NanoAtlas&, std::string const&, std::string const&) () from /home/ryan/stuff/kiui/src/libkiui.so
#2  0x00007ffff7a62910 in mk::generateAtlas(NVGcontext*, unsigned long, unsigned long, std::string) () from /home/ryan/stuff/kiui/src/libkiui.so
#3  0x00007ffff7a63eec in mk::NanoWindow::NanoWindow(unsigned long, unsigned long, float, std::string) () from /home/ryan/stuff/kiui/src/libkiui.so
#4  0x00007ffff7a710ff in mk::make_unique<mk::NanoWindow, unsigned int&, unsigned int&, float&, std::string&> () from /home/ryan/stuff/kiui/src/libkiui.so
#5  0x00007ffff7a70399 in mk::GlWindow::initContext() ()
   from /home/ryan/stuff/kiui/src/libkiui.so
#6  0x0000000000412d67 in main ()