--- a/py2pack/requires.py
+++ b/py2pack/requires.py
@@ -52,7 +52,7 @@
         else:
             os.chdir(tmp_dir)
         # generate a temporary json file which contains the metadata
-        cmd = "python setup.py -q --command-packages py2pack " \
+        cmd = "python3 setup.py -q --command-packages py2pack " \
               "get_metadata -o %s " % tempfile_json.name
         try:
             subprocess.check_output(cmd, stderr=subprocess.STDOUT, shell=True)