diff --git a/tools/project.py b/tools/project.py
index 87dba9d5b4..b9f9e3f63f 100644
--- a/tools/project.py
+++ b/tools/project.py
@@ -167,7 +167,7 @@ def get_args(argv):
 
     targetnames = TARGET_NAMES
     targetnames.sort()
-    toolchainlist = list(EXPORTERS.keys() + EXPORTER_ALIASES.keys())
+    toolchainlist = list(EXPORTERS.keys()) + list(EXPORTER_ALIASES.keys())
     toolchainlist.sort()
 
     parser.add_argument(