diff --git a/support/testing/infra/basetest.py b/support/testing/infra/basetest.py
index 5014fefafa..e67bf1af23 100644
--- a/support/testing/infra/basetest.py
+++ b/support/testing/infra/basetest.py
@@ -30,6 +30,7 @@ MINIMAL_CONFIG = \
 
 class BRTest(unittest.TestCase):
     config = None
+    br2_external = list()
     downloaddir = None
     outputdir = None
     logtofile = True
@@ -58,7 +59,7 @@ class BRTest(unittest.TestCase):
 
         if not self.b.is_finished():
             self.show_msg("Building")
-            self.b.configure()
+            self.b.configure(make_extra_opts=["BR2_EXTERNAL={}".format(":".join(self.br2_external))])
             self.b.build()
             self.show_msg("Building done")