diff --git a/rust/project_json_test.go b/rust/project_json_test.go
index bdd54c5..f7b6681 100644
--- a/rust/project_json_test.go
+++ b/rust/project_json_test.go
@@ -36,7 +36,7 @@
 	// The JSON file is generated via WriteFileToOutputDir. Therefore, it
 	// won't appear in the Output of the TestingSingleton. Manually verify
 	// it exists.
-	content, err := ioutil.ReadFile(filepath.Join(result.Config.BuildDir(), rustProjectJsonFileName))
+	content, err := ioutil.ReadFile(filepath.Join(result.Config.SoongOutDir(), rustProjectJsonFileName))
 	if err != nil {
 		t.Errorf("rust-project.json has not been generated")
 	}