diff --git a/BUILD.gn b/BUILD.gn
index 653902c..865db6a 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -41,6 +41,7 @@
 
 python_library("antlion") {
   source_root = "//third_party/antlion/packages/antlion"
+  testonly = true
   sources = [
     "__init__.py",
     "base_test.py",