diff --git a/build/android/pylib/local/device/local_device_instrumentation_test_run.py b/build/android/pylib/local/device/local_device_instrumentation_test_run.py
index d5426bc3e66d5..87f0a04471960 100644
--- a/build/android/pylib/local/device/local_device_instrumentation_test_run.py
+++ b/build/android/pylib/local/device/local_device_instrumentation_test_run.py
@@ -63,7 +63,7 @@ def substitute_device_root(d, device_root):
       if not d:
         return device_root
       elif isinstance(d, list):
-        return posixpath.join(p if p else device_root for p in d)
+        return posixpath.join(*(p if p else device_root for p in d))
       else:
         return d