diff --git a/src/librustc/lint/builtin.rs b/src/librustc/lint/builtin.rs
index cbe642a9a76a..811bf9776101 100644
--- a/src/librustc/lint/builtin.rs
+++ b/src/librustc/lint/builtin.rs
@@ -30,7 +30,7 @@ declare_lint! {
 
 declare_lint! {
     pub UNUSED_EXTERN_CRATES,
-    Allow,
+    Warn,
     "extern crates that are never used"
 }