diff --git a/BUILD b/BUILD
index 56f9ea38f8..d08b7a09e1 100644
--- a/BUILD
+++ b/BUILD
@@ -570,6 +570,7 @@ java_library(
     ]) + [
         ":gen_well_known_protos_java",
     ],
+    javacopts = ["-source 6"],
     visibility = ["//visibility:public"],
 )