diff --git a/src/librustc/middle/borrowck/mod.rs b/src/librustc/middle/borrowck/mod.rs
index 431b7b0e2c8..d0a3be055d1 100644
--- a/src/librustc/middle/borrowck/mod.rs
+++ b/src/librustc/middle/borrowck/mod.rs
@@ -475,7 +475,8 @@ impl BorrowckCtxt {
     }
 
     pub fn is_move(&self, id: ast::NodeId) -> bool {
-        self.moves_map.contains(&id)
+        let moves_map = self.moves_map.borrow();
+        moves_map.get().contains(&id)
     }
 
     pub fn cat_expr(&self, expr: @ast::Expr) -> mc::cmt {
diff --git a/src/librustc/middle/check_match.rs b/src/librustc/middle/check_match.rs
index 948c7932ca0..116d0155084 100644
--- a/src/librustc/middle/check_match.rs
+++ b/src/librustc/middle/check_match.rs
@@ -889,7 +889,8 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
                     by_ref_span = Some(span);
                 }
                 BindByValue(_) => {
-                    if cx.moves_map.contains(&id) {
+                    let moves_map = cx.moves_map.borrow();
+                    if moves_map.get().contains(&id) {
                         any_by_move = true;
                     }
                 }
@@ -926,7 +927,8 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
             if pat_is_binding(def_map, p) {
                 match p.node {
                     PatIdent(_, _, sub) => {
-                        if cx.moves_map.contains(&p.id) {
+                        let moves_map = cx.moves_map.borrow();
+                        if moves_map.get().contains(&p.id) {
                             check_move(p, sub);
                         }
                     }
diff --git a/src/librustc/middle/moves.rs b/src/librustc/middle/moves.rs
index f36b283f1e4..29e59ba5c45 100644
--- a/src/librustc/middle/moves.rs
+++ b/src/librustc/middle/moves.rs
@@ -161,7 +161,7 @@ pub struct CaptureVar {
 
 pub type CaptureMap = @RefCell<HashMap<NodeId, @[CaptureVar]>>;
 
-pub type MovesMap = @mut HashSet<NodeId>;
+pub type MovesMap = @RefCell<HashSet<NodeId>>;
 
 /**
  * Set of variable node-ids that are moved.
@@ -215,7 +215,7 @@ pub fn compute_moves(tcx: ty::ctxt,
         tcx: tcx,
         method_map: method_map,
         move_maps: MoveMaps {
-            moves_map: @mut HashSet::new(),
+            moves_map: @RefCell::new(HashSet::new()),
             capture_map: @RefCell::new(HashMap::new()),
             moved_variables_set: @mut HashSet::new()
         }
@@ -283,7 +283,10 @@ impl VisitContext {
 
         let expr_ty = ty::expr_ty_adjusted(self.tcx, expr);
         if ty::type_moves_by_default(self.tcx, expr_ty) {
-            self.move_maps.moves_map.insert(expr.id);
+            {
+                let mut moves_map = self.move_maps.moves_map.borrow_mut();
+                moves_map.get().insert(expr.id);
+            }
             self.use_expr(expr, Move);
         } else {
             self.use_expr(expr, Read);
@@ -388,7 +391,12 @@ impl VisitContext {
                 // closures should be noncopyable, they shouldn't move by default;
                 // calling a closure should only consume it if it's once.
                 if mode == Move {
-                    self.move_maps.moves_map.insert(callee.id);
+                    {
+                        let mut moves_map = self.move_maps
+                                                .moves_map
+                                                .borrow_mut();
+                        moves_map.get().insert(callee.id);
+                    }
                 }
                 self.use_expr(callee, mode);
                 self.use_fn_args(callee.id, *args);
@@ -643,7 +651,10 @@ impl VisitContext {
                    id, bm, binding_moves);
 
             if binding_moves {
-                self.move_maps.moves_map.insert(id);
+                {
+                    let mut moves_map = self.move_maps.moves_map.borrow_mut();
+                    moves_map.get().insert(id);
+                }
             }
         })
     }