[Cython] Improving compile times for Cython extensions with C sources

I haven't been able to find an easy answer to this question, but here is my problem: Cython file: extension.pyx Declarations / C imports: extension.pxd C dependencies: a.c b.c c.c These are all compiled together to produce extension.so. The problem is, when I modify extension.pyx, all 4 C files are recompiled, even if the 3 straight C files are untouched. Any way to fix the build system to not do this? Seems that the .o files from the C dependencies could be easily reused. thanks, Wes