Index: gen-make.py
===================================================================
--- gen-make.py	(revision 1515099)
+++ gen-make.py	(working copy)
@@ -278,6 +278,9 @@ if __name__ == '__main__':
   except getopt.GetoptError, e:
     _usage_exit(str(e))
 
+  if args and args[0] and os.path.exists(args[0]) != True:
+    _usage_exit("argument must be a path to build.conf file")
+
   conf = 'build.conf'
   skip = 0
   gentype = 'make'