MDN’s new design is in Beta! A sneak peek:

pybuild is no longer supported! See bug 1027890. (and the pymake modules that support it) are an implementation of the make tool which are mostly compatible with makefiles written for GNU make.


If running Windows, you need to have a Windows build environment installed for using pymake to build Mozilla.

On other operating systems (Linux, OS X, etc), pymake itself only requires Python 2.6 or higher (but not Python 3). Please note that Python 2.7 is strongly recommended.


If you use mach for everything, you don't have to worry about gmake and pymake: mach will run whatever is best for the current machine.

Note: On Windows, you must take special care to be able to switch back and forth between gmake and pymake on the same object dir. See Gmake vs. Pymake for more information.

Anywhere you would normally type make, instead type python /path/to/srcdir/build/pymake/  For example:

  • Instead of make -f to start a build, you would type python build/pymake/ -f
  • To run tests instead of typing make mochitest-plain in the object directory, you would type python ../build/pymake/ mochitest-plain.

Alternately, if you would like to simply type in pymake -f from within the MINGW32 shell.

  • While in the shell type cd ~ (without quotes).
  • Type touch .profile
  • Using any appropriate text editor open .profile and add the following line in the file (assuming your mozilla-central is at C:/mozilla-central, if not, adjust your path accordingly.)

alias pymake=C:/mozilla-central/build/pymake/

  • Save your .profile edit and close the shell, then restart the shell.
  • Try typing just pymake into the shell and press enter.  This should come back with "No makefile found." If it does, your pymake alias is connected and you are ready to type in pymake -f to start the build.

Unlike gmake on Windows, pymake is capable of doing parallel builds, so you can set a MOZ_MAKE_FLAGS=-jN in your .mozconfig without risk of deadlocks.

Note: On Windows, if using an absolute path MOZ_OBJDIR in your .mozconfig, it must be a Windows-style (i.e. c:/foo/bar) rather than an MSYS-style (i.e. /c/foo/bar) path.

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 Last updated by: jmozmoz,