diff --git a/src/librustc_trans/back/link.rs b/src/librustc_trans/back/link.rs
index 93ff9f53ec1..c3c97616ea8 100644
--- a/src/librustc_trans/back/link.rs
+++ b/src/librustc_trans/back/link.rs
@@ -266,7 +266,7 @@ pub fn sanitize(s: &str) -> String {
     return result;
 }
 
-pub fn mangle<PI: Iterator<PathElem>>(mut path: PI,
+pub fn mangle<PI: Iterator<Item=PathElem>>(mut path: PI,
                                       hash: Option<&str>) -> String {
     // Follow C++ namespace-mangling style, see
     // http://en.wikipedia.org/wiki/Name_mangling for more info.
diff --git a/src/librustc_trans/lib.rs b/src/librustc_trans/lib.rs
index 5ffe9b2d647..9dbff66aba2 100644
--- a/src/librustc_trans/lib.rs
+++ b/src/librustc_trans/lib.rs
@@ -28,6 +28,7 @@
 #![feature(rustc_diagnostic_macros)]
 #![feature(unboxed_closures)]
 #![feature(old_orphan_check)]
+#![feature(associated_types)]
 
 extern crate arena;
 extern crate flate;
diff --git a/src/librustc_trans/trans/base.rs b/src/librustc_trans/trans/base.rs
index bf53885e9e5..d1cb22dce38 100644
--- a/src/librustc_trans/trans/base.rs
+++ b/src/librustc_trans/trans/base.rs
@@ -3070,7 +3070,9 @@ fn internalize_symbols(cx: &SharedCrateContext, reachable: &HashSet<String>) {
         step: unsafe extern "C" fn(ValueRef) -> ValueRef,
     }
 
-    impl Iterator<ValueRef> for ValueIter {
+    impl Iterator for ValueIter {
+        type Item = ValueRef;
+
         fn next(&mut self) -> Option<ValueRef> {
             let old = self.cur;
             if !old.is_null() {
diff --git a/src/librustc_trans/trans/context.rs b/src/librustc_trans/trans/context.rs
index 9ceb0c63990..67aecde6618 100644
--- a/src/librustc_trans/trans/context.rs
+++ b/src/librustc_trans/trans/context.rs
@@ -168,7 +168,9 @@ pub struct CrateContextIterator<'a, 'tcx: 'a> {
     index: uint,
 }
 
-impl<'a, 'tcx> Iterator<CrateContext<'a, 'tcx>> for CrateContextIterator<'a,'tcx> {
+impl<'a, 'tcx> Iterator for CrateContextIterator<'a,'tcx> {
+    type Item = CrateContext<'a, 'tcx>;
+
     fn next(&mut self) -> Option<CrateContext<'a, 'tcx>> {
         if self.index >= self.shared.local_ccxs.len() {
             return None;
@@ -193,7 +195,9 @@ pub struct CrateContextMaybeIterator<'a, 'tcx: 'a> {
     origin: uint,
 }
 
-impl<'a, 'tcx> Iterator<(CrateContext<'a, 'tcx>, bool)> for CrateContextMaybeIterator<'a, 'tcx> {
+impl<'a, 'tcx> Iterator for CrateContextMaybeIterator<'a, 'tcx> {
+    type Item = (CrateContext<'a, 'tcx>, bool);
+
     fn next(&mut self) -> Option<(CrateContext<'a, 'tcx>, bool)> {
         if self.index >= self.shared.local_ccxs.len() {
             return None;
diff --git a/src/librustc_trans/trans/meth.rs b/src/librustc_trans/trans/meth.rs
index 99624f1b1e7..f0588b3082a 100644
--- a/src/librustc_trans/trans/meth.rs
+++ b/src/librustc_trans/trans/meth.rs
@@ -727,7 +727,7 @@ pub fn get_vtable<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
 }
 
 /// Helper function to declare and initialize the vtable.
-pub fn make_vtable<I: Iterator<ValueRef>>(ccx: &CrateContext,
+pub fn make_vtable<I: Iterator<Item=ValueRef>>(ccx: &CrateContext,
                                           drop_glue: ValueRef,
                                           size: ValueRef,
                                           align: ValueRef,
diff --git a/src/librustc_trans/trans/value.rs b/src/librustc_trans/trans/value.rs
index 9e959ce4221..028e2154303 100644
--- a/src/librustc_trans/trans/value.rs
+++ b/src/librustc_trans/trans/value.rs
@@ -155,7 +155,9 @@ pub struct Users {
     next: Option<Use>
 }
 
-impl Iterator<Value> for Users {
+impl Iterator for Users {
+    type Item = Value;
+
     fn next(&mut self) -> Option<Value> {
         let current = self.next;