diff --git a/3rdparty/libbacktrace/wscript b/3rdparty/libbacktrace/wscript
index d32d8153..5906f8f7 100644
--- a/3rdparty/libbacktrace/wscript
+++ b/3rdparty/libbacktrace/wscript
@@ -148,8 +148,7 @@ def configure(conf):
 	conf.write_config_header('backtrace-supported.h')
 
 @TaskGen.feature('frandomseed')
-@TaskGen.after_method('process_source')
-@TaskGen.before_method('apply_link')
+@TaskGen.after_method('propagate_uselib_vars')
 def process_frandom_seed(ctx):
 	tasks = getattr(ctx, 'compiled_tasks', [])
 
diff --git a/wscript b/wscript
index 0c2b0583..6f355f4d 100644
--- a/wscript
+++ b/wscript
@@ -532,7 +532,7 @@ def build(bld):
 
 	# don't clean QtCreator files and reconfigure saved options
 	bld.clean_files = bld.bldnode.ant_glob('**',
-		excl='*.user configuration.py .lock* *conf_check_*/** config.log %s/*' % Build.CACHE_DIR,
+		excl='*.user configuration.py .lock* *conf_check_*/** config.log 3rdparty/libbacktrace/*.h %s/*' % Build.CACHE_DIR,
 		quiet=True, generator=True)
 
 	bld.load('xshlib')