diff --git a/tools/BUILD b/tools/BUILD
index 7dd7f04cc..9025e0a6d 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -29,7 +29,7 @@ java_package_configuration(
         "-Xep:BadComparable:WARN",
         "-Xep:BoxedPrimitiveConstructor:ERROR",
         "-Xep:CannotMockFinalClass:WARN",
-        "-Xep:ClassCanBeStatic:WARN",
+        "-Xep:ClassCanBeStatic:ERROR",
         "-Xep:ClassNewInstance:WARN",
         "-Xep:DefaultCharset:ERROR",
         "-Xep:DoubleCheckedLocking:WARN",