diff --git a/src/consts.rs b/src/consts.rs
index c033888e360..70d5ff4bc17 100644
--- a/src/consts.rs
+++ b/src/consts.rs
@@ -67,7 +67,7 @@ impl Constant {
     }
 
     /// convert this constant to a f64, if possible
-    #[allow(unknown_lints,cast_precision_loss)]
+    #[allow(cast_precision_loss)]
     pub fn as_float(&self) -> Option<f64> {
         match *self {
             ConstantByte(b) => Some(b as f64),
diff --git a/src/lib.rs b/src/lib.rs
index 1b4d77dacca..f4e3ed54c60 100755
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 #![feature(plugin_registrar, box_syntax)]
 #![feature(rustc_private, core, collections)]
 #![feature(str_split_at)]
+#![allow(unknown_lints)]
 
 #[macro_use]
 extern crate syntax;