diff --git a/src/librustc/middle/dead.rs b/src/librustc/middle/dead.rs
index 90d26f0f6bf53..cf680871dcf22 100644
--- a/src/librustc/middle/dead.rs
+++ b/src/librustc/middle/dead.rs
@@ -234,7 +234,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
             ast_map::NodeImplItem(impl_item) => {
                 match *impl_item {
                     ast::MethodImplItem(ref method) => {
-                        visit::walk_block(self, method.pe_body());
+                        visit::walk_method_helper(self, method);
                     }
                     ast::TypeImplItem(_) => {}
                 }
diff --git a/src/test/run-pass/issue-20343.rs b/src/test/run-pass/issue-20343.rs
new file mode 100644
index 0000000000000..79034a4a4a6d6
--- /dev/null
+++ b/src/test/run-pass/issue-20343.rs
@@ -0,0 +1,38 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Regression test for Issue #20343.
+
+#![deny(dead_code)]
+
+struct B { b: u32 }
+struct C;
+struct D;
+
+trait T<A> {}
+impl<A> T<A> for () {}
+
+impl B {
+    // test for unused code in arguments
+    fn foo(B { b }: B) -> u32 { b }
+
+    // test for unused code in return type
+    fn bar() -> C { unsafe { ::std::mem::transmute(()) } }
+
+    // test for unused code in generics
+    fn baz<A: T<D>>() {}
+}
+
+pub fn main() {
+    let b = B { b: 3 };
+    B::foo(b);
+    B::bar();
+    B::baz::<()>();
+}