diff --git a/src/librustc/metadata/decoder.rs b/src/librustc/metadata/decoder.rs
index 69faf519bc280..b08186349319d 100644
--- a/src/librustc/metadata/decoder.rs
+++ b/src/librustc/metadata/decoder.rs
@@ -786,7 +786,7 @@ fn get_explicit_self(item: ebml::Doc) -> ast::explicit_self_ {
         's' => { return ast::sty_static; }
         'v' => { return ast::sty_value; }
         '@' => { return ast::sty_box(get_mutability(string[1])); }
-        '~' => { return ast::sty_uniq(get_mutability(string[1])); }
+        '~' => { return ast::sty_uniq; }
         '&' => {
             // FIXME(#4846) expl. region
             return ast::sty_region(None, get_mutability(string[1]));
diff --git a/src/librustc/metadata/encoder.rs b/src/librustc/metadata/encoder.rs
index e394c8dcf92f9..7735a7e39561f 100644
--- a/src/librustc/metadata/encoder.rs
+++ b/src/librustc/metadata/encoder.rs
@@ -630,9 +630,8 @@ fn encode_explicit_self(ebml_w: &mut writer::Encoder, explicit_self: ast::explic
             ebml_w.writer.write(&[ '@' as u8 ]);
             encode_mutability(ebml_w, m);
         }
-        sty_uniq(m) => {
+        sty_uniq => {
             ebml_w.writer.write(&[ '~' as u8 ]);
-            encode_mutability(ebml_w, m);
         }
     }
 
diff --git a/src/librustc/middle/check_const.rs b/src/librustc/middle/check_const.rs
index 2c6ba79e96e45..8ad61fe1f61cd 100644
--- a/src/librustc/middle/check_const.rs
+++ b/src/librustc/middle/check_const.rs
@@ -92,7 +92,7 @@ pub fn check_expr(sess: Session,
     if is_const {
         match e.node {
           expr_unary(_, deref, _) => { }
-          expr_unary(_, box(_), _) | expr_unary(_, uniq(_), _) => {
+          expr_unary(_, box(_), _) | expr_unary(_, uniq, _) => {
             sess.span_err(e.span,
                           "disallowed operator in constant expression");
             return;
diff --git a/src/librustc/middle/liveness.rs b/src/librustc/middle/liveness.rs
index 86b8b2943198e..e431784f1e63a 100644
--- a/src/librustc/middle/liveness.rs
+++ b/src/librustc/middle/liveness.rs
@@ -368,7 +368,7 @@ fn visit_fn(fk: &visit::fn_kind,
     match *fk {
         fk_method(_, _, method) => {
             match method.explicit_self.node {
-                sty_value | sty_region(*) | sty_box(_) | sty_uniq(_) => {
+                sty_value | sty_region(*) | sty_box(_) | sty_uniq => {
                     fn_maps.add_variable(Arg(method.self_id,
                                              special_idents::self_));
                 }
diff --git a/src/librustc/middle/trans/consts.rs b/src/librustc/middle/trans/consts.rs
index d7b6e9cf5a372..6780c51e5062a 100644
--- a/src/librustc/middle/trans/consts.rs
+++ b/src/librustc/middle/trans/consts.rs
@@ -340,7 +340,7 @@ fn const_expr_unadjusted(cx: @mut CrateContext, e: &ast::expr) -> ValueRef {
             let is_float = ty::type_is_fp(ty);
             return match u {
               ast::box(_)  |
-              ast::uniq(_) |
+              ast::uniq |
               ast::deref  => {
                 let (dv, _dt) = const_deref(cx, te, ty, true);
                 dv
diff --git a/src/librustc/middle/trans/expr.rs b/src/librustc/middle/trans/expr.rs
index 3532273075602..297a466c7cb0a 100644
--- a/src/librustc/middle/trans/expr.rs
+++ b/src/librustc/middle/trans/expr.rs
@@ -1314,7 +1314,7 @@ fn trans_unary_datum(bcx: block,
             trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty,
                              heap_managed)
         }
-        ast::uniq(_) => {
+        ast::uniq => {
             let heap  = heap_for_unique(bcx, un_ty);
             trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty, heap)
         }
diff --git a/src/librustc/middle/trans/meth.rs b/src/librustc/middle/trans/meth.rs
index 0b051662781e0..75e9dbe48619d 100644
--- a/src/librustc/middle/trans/meth.rs
+++ b/src/librustc/middle/trans/meth.rs
@@ -532,7 +532,7 @@ pub fn trans_trait_callee(bcx: block,
     let llpair = match explicit_self {
         ast::sty_region(*) => Load(bcx, llpair),
         ast::sty_static | ast::sty_value |
-        ast::sty_box(_) | ast::sty_uniq(_) => llpair
+        ast::sty_box(_) | ast::sty_uniq => llpair
     };
 
     let callee_ty = node_id_type(bcx, callee_id);
@@ -622,7 +622,7 @@ pub fn trans_trait_callee_from_llval(bcx: block,
 
             self_mode = ty::ByRef;
         }
-        ast::sty_uniq(_) => {
+        ast::sty_uniq => {
             // Pass the unique pointer.
             match store {
                 ty::UniqTraitStore => llself = llbox,
diff --git a/src/librustc/middle/trans/type_use.rs b/src/librustc/middle/trans/type_use.rs
index c636b7f48761f..d8d5397646203 100644
--- a/src/librustc/middle/trans/type_use.rs
+++ b/src/librustc/middle/trans/type_use.rs
@@ -278,7 +278,7 @@ pub fn mark_for_method_call(cx: &Context, e_id: node_id, callee_id: node_id) {
 pub fn mark_for_expr(cx: &Context, e: &expr) {
     match e.node {
       expr_vstore(_, _) | expr_vec(_, _) | expr_struct(*) | expr_tup(_) |
-      expr_unary(_, box(_), _) | expr_unary(_, uniq(_), _) |
+      expr_unary(_, box(_), _) | expr_unary(_, uniq, _) |
       expr_binary(_, add, _, _) | expr_copy(_) | expr_repeat(*) => {
         node_type_needs(cx, use_repr, e.id);
       }
diff --git a/src/librustc/middle/typeck/astconv.rs b/src/librustc/middle/typeck/astconv.rs
index 07fb23fea48a3..1e236c620a0e5 100644
--- a/src/librustc/middle/typeck/astconv.rs
+++ b/src/librustc/middle/typeck/astconv.rs
@@ -662,10 +662,10 @@ fn ty_of_method_or_bare_fn<AC:AstConv,RS:region_scope + Copy + 'static>(
                                 ty::mt {ty: self_info.untransformed_self_ty,
                                         mutbl: mutability}))
             }
-            ast::sty_uniq(mutability) => {
+            ast::sty_uniq => {
                 Some(ty::mk_uniq(this.tcx(),
                                  ty::mt {ty: self_info.untransformed_self_ty,
-                                         mutbl: mutability}))
+                                         mutbl: ast::m_imm}))
             }
         }
     }
diff --git a/src/librustc/middle/typeck/check/method.rs b/src/librustc/middle/typeck/check/method.rs
index 4bebca3c9a8b3..7489882ab768c 100644
--- a/src/librustc/middle/typeck/check/method.rs
+++ b/src/librustc/middle/typeck/check/method.rs
@@ -1123,11 +1123,11 @@ impl<'self> LookupContext<'self> {
                 }
             }
 
-            sty_uniq(m) => {
+            sty_uniq => {
                 debug!("(is relevant?) explicit self is a unique pointer");
                 match ty::get(rcvr_ty).sty {
                     ty::ty_uniq(mt) => {
-                        mutability_matches(mt.mutbl, m) &&
+                        mutability_matches(mt.mutbl, ast::m_imm) &&
                         self.fcx.can_mk_subty(mt.ty, candidate.rcvr_ty).is_ok()
                     }
 
diff --git a/src/librustc/middle/typeck/check/mod.rs b/src/librustc/middle/typeck/check/mod.rs
index 23266767124c8..0cd9aac379892 100644
--- a/src/librustc/middle/typeck/check/mod.rs
+++ b/src/librustc/middle/typeck/check/mod.rs
@@ -2301,7 +2301,7 @@ pub fn check_expr_with_unifier(fcx: @mut FnCtxt,
       ast::expr_unary(callee_id, unop, oprnd) => {
         let exp_inner = do unpack_expected(fcx, expected) |sty| {
             match unop {
-              ast::box(_) | ast::uniq(_) => match *sty {
+              ast::box(_) | ast::uniq => match *sty {
                 ty::ty_box(ref mt) | ty::ty_uniq(ref mt) => Some(mt.ty),
                 _ => None
               },
@@ -2318,9 +2318,10 @@ pub fn check_expr_with_unifier(fcx: @mut FnCtxt,
                     oprnd_t = ty::mk_box(tcx,
                                          ty::mt {ty: oprnd_t, mutbl: mutbl});
                 }
-                ast::uniq(mutbl) => {
+                ast::uniq => {
                     oprnd_t = ty::mk_uniq(tcx,
-                                          ty::mt {ty: oprnd_t, mutbl: mutbl});
+                                          ty::mt {ty: oprnd_t,
+                                                  mutbl: ast::m_imm});
                 }
                 ast::deref => {
                     let sty = structure_of(fcx, expr.span, oprnd_t);
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index bc432c4c7b0b6..2603cbb2dd7c5 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -333,7 +333,7 @@ pub enum binop {
 #[deriving(Eq, Encodable, Decodable,IterBytes)]
 pub enum unop {
     box(mutability),
-    uniq(mutability),
+    uniq,
     deref,
     not,
     neg
@@ -805,7 +805,7 @@ pub enum explicit_self_ {
     sty_value,                                 // `self`
     sty_region(Option<@Lifetime>, mutability), // `&'lt self`
     sty_box(mutability),                       // `@self`
-    sty_uniq(mutability)                       // `~self`
+    sty_uniq                                   // `~self`
 }
 
 pub type explicit_self = spanned<explicit_self_>;
diff --git a/src/libsyntax/ast_util.rs b/src/libsyntax/ast_util.rs
index 9439f45be21bf..ee7c7180f8db2 100644
--- a/src/libsyntax/ast_util.rs
+++ b/src/libsyntax/ast_util.rs
@@ -135,7 +135,7 @@ pub fn is_shift_binop(b: binop) -> bool {
 pub fn unop_to_str(op: unop) -> ~str {
     match op {
       box(mt) => if mt == m_mutbl { ~"@mut " } else { ~"@" },
-      uniq(mt) => if mt == m_mutbl { ~"~mut " } else { ~"~" },
+      uniq => ~"~",
       deref => ~"*",
       not => ~"!",
       neg => ~"-"
diff --git a/src/libsyntax/ext/deriving/ty.rs b/src/libsyntax/ext/deriving/ty.rs
index a2f9aa58d99ad..e210853bfb4dc 100644
--- a/src/libsyntax/ext/deriving/ty.rs
+++ b/src/libsyntax/ext/deriving/ty.rs
@@ -248,7 +248,7 @@ pub fn get_explicit_self(cx: @ExtCtxt, span: span, self_ptr: &Option<PtrTy>)
             let self_ty = respan(
                 span,
                 match *ptr {
-                    Send => ast::sty_uniq(ast::m_imm),
+                    Send => ast::sty_uniq,
                     Managed(mutbl) => ast::sty_box(mutbl),
                     Borrowed(ref lt, mutbl) => {
                         let lt = lt.map(|s| @cx.lifetime(span,
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index f1b5c4d16be97..cc0baa28e20d7 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -2071,9 +2071,8 @@ impl Parser {
             ex = match e.node {
               expr_vec(*) |
               expr_lit(@codemap::spanned { node: lit_str(_), span: _}) |
-              expr_repeat(*)
-              if m == m_imm => expr_vstore(e, expr_vstore_uniq),
-              _ => self.mk_unary(uniq(m), e)
+              expr_repeat(*) => expr_vstore(e, expr_vstore_uniq),
+              _ => self.mk_unary(uniq, e)
             };
           }
           _ => return self.parse_dot_or_call_expr()
@@ -3366,7 +3365,12 @@ impl Parser {
             maybe_parse_explicit_self(sty_box, self)
           }
           token::TILDE => {
-            maybe_parse_explicit_self(sty_uniq, self)
+            maybe_parse_explicit_self(|mutability| {
+                if mutability != m_imm {
+                    self.obsolete(*self.last_span, ObsoleteMutOwnedPointer);
+                }
+                sty_uniq
+            }, self)
           }
           token::IDENT(*) if self.is_self_ident() => {
             self.bump();
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 9a1682bf063d7..978561eaa67c6 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -1653,6 +1653,7 @@ pub fn print_explicit_self(s: @ps, explicit_self: ast::explicit_self_) -> bool {
     match explicit_self {
         ast::sty_static => { return false; }
         ast::sty_value => { word(s.s, "self"); }
+        ast::sty_uniq => { word(s.s, "~self"); }
         ast::sty_region(lt, m) => {
             word(s.s, "&");
             print_opt_lifetime(s, lt);
@@ -1662,9 +1663,6 @@ pub fn print_explicit_self(s: @ps, explicit_self: ast::explicit_self_) -> bool {
         ast::sty_box(m) => {
             word(s.s, "@"); print_mutability(s, m); word(s.s, "self");
         }
-        ast::sty_uniq(m) => {
-            word(s.s, "~"); print_mutability(s, m); word(s.s, "self");
-        }
     }
     return true;
 }