diff --git a/3rdparty/libbacktrace/wscript b/3rdparty/libbacktrace/wscript
index 5906f8f7..8cfc1d0f 100644
--- a/3rdparty/libbacktrace/wscript
+++ b/3rdparty/libbacktrace/wscript
@@ -2,6 +2,7 @@
 # encoding: utf-8
 
 from waflib import TaskGen
+from waflib.Tools.c_config import DEFKEYS
 
 FRAGMENT_ATOMIC='''int i;
 int main(void) {
@@ -138,6 +139,8 @@ def configure(conf):
 		msg='Checking for in parallel'
 	)
 
+	conf.env[DEFKEYS].sort()
+
 	conf.write_config_header()
 
 	conf.define('BACKTRACE_SUPPORTED', 1)