diff --git a/tools/pycps.BUILD b/tools/pycps.BUILD
index c419bf27f4b2..dcf40055e370 100644
--- a/tools/pycps.BUILD
+++ b/tools/pycps.BUILD
@@ -9,6 +9,7 @@ py_library(
   name = "cps",
   srcs = ["cps.py"],
   deps = ["@semantic_version//:semantic_version"],
+  visibility = ["//visibility:private"], # LGPL; don't use externally
 )
 
 py_binary(