--- a/build/moz.configure/old.configure
+++ b/build/moz.configure/old.configure
@@ -99,16 +99,18 @@ def prepare_configure(old_configure, moz
             refresh = False
 
     if refresh:
         log.info('Refreshing %s with %s', old_configure, autoconf)
         script = subprocess.check_output([
             shell, autoconf,
             '--localdir=%s' % os.path.dirname(old_configure),
             old_configure + '.in'])
+        if not script:
+            die('Generated old-configure is empty! Check that your autoconf 2.13 and awk programs work!')
 
         # Make old-configure append to config.log, where we put our own log.
         # This could be done with a m4 macro, but it's way easier this way
         script = script.replace('>./config.log', '>>./config.log')
 
         with open(old_configure, 'wb') as fh:
             fh.write(script)