diff --git a/tools/BUILD b/tools/BUILD
index a271020d18..8648c2f7f7 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -65,6 +65,7 @@ java_package_configuration(
         "-Xep:NullableConstructor:WARN",
         "-Xep:NullablePrimitive:WARN",
         "-Xep:NullableVoid:WARN",
+        "-Xep:ObjectToString:ERROR",
         "-Xep:OperatorPrecedence:ERROR",
         "-Xep:OverridesGuiceInjectableMethod:WARN",
         "-Xep:PreconditionsInvalidPlaceholder:WARN",