diff --git a/java/testing.go b/java/testing.go
index e6f76e1..63d7dba 100644
--- a/java/testing.go
+++ b/java/testing.go
@@ -198,7 +198,7 @@
 				imports_sdk_version: "none",
 				imports_compile_dex: true,
 			}
-		`, strings.Join(android.SortedStringKeys(apiLevel2Modules), `", "`))
+		`, strings.Join(android.SortedKeys(apiLevel2Modules), `", "`))
 
 	for release, modules := range apiLevel2Modules {
 		mockFS.Merge(prebuiltApisFilesForModules([]string{release}, modules))