diff --git a/hb/build/build_process.py b/hb/build/build_process.py
index 71679eddbe62af24cb1150bb3964754027d2be7a..53fbb49791e6b36bafc57121006da7c1a2c869ad 100755
--- a/hb/build/build_process.py
+++ b/hb/build/build_process.py
@@ -141,6 +141,7 @@ class Build():
                   self.config.out_path,
                   '--root={}'.format(self.config.root_path),
                   '--dotfile={}/.gn'.format(self.config.build_path),
+                  '--script-executable=python3',
                   '--args={}'.format(" ".join(self._args_list))] + gn_args
         exec_command(gn_cmd, log_path=self.config.log_path)