diff --git a/dapps/js-glue/src/codegen.rs b/dapps/js-glue/src/codegen.rs
index 3d8c93460..c6e948820 100644
--- a/dapps/js-glue/src/codegen.rs
+++ b/dapps/js-glue/src/codegen.rs
@@ -101,6 +101,7 @@ fn implement_webapp(cx: &ExtCtxt, builder: &aster::AstBuilder, item: &Item, push
 
 	let files_impl = quote_item!(cx,
 		impl $type_name {
+			#[allow(unused_mut)]
 			fn files() -> ::std::collections::HashMap<&'static str, File> {
 				let mut files = ::std::collections::HashMap::new();
 				$statements
diff --git a/util/hash/build.rs b/util/hash/build.rs
index 2370855fe..fe7965a61 100644
--- a/util/hash/build.rs
+++ b/util/hash/build.rs
@@ -21,6 +21,6 @@
 extern crate gcc;
 
 fn main() {
-    gcc::compile_library("libtinykeccak.a", &["src/tinykeccak.c"]);
+    gcc::Build::new().file("src/tinykeccak.c").compile("libtinykeccak.a");
 }