diff --git a/src/rustc/middle/trans/tvec.rs b/src/rustc/middle/trans/tvec.rs
index fa21927d743283cc0e13fdddba9f294e451628d9..125fc8d30dfa80dc1de2abcd1b18c4c7b0f7b250 100644
--- a/src/rustc/middle/trans/tvec.rs
+++ b/src/rustc/middle/trans/tvec.rs
@@ -57,17 +57,14 @@ fn alloc_uniq_raw(bcx: block, unit_ty: ty::t,
                   fill: ValueRef, alloc: ValueRef) -> result {
     let _icx = bcx.insn_ctxt("tvec::alloc_uniq_raw");
     let ccx = bcx.ccx();
-    let llunitty = type_of::type_of(ccx, unit_ty);
-    let llvecty = T_vec(ccx, llunitty);
-    let vecsize = Add(bcx, alloc, llsize_of(ccx, llvecty));
-    let vecbodyty = unit_ty; // FIXME: This is not the correct type (#2536)
+
+    let vecbodyty = ty::mk_mut_unboxed_vec(bcx.tcx(), unit_ty);
+    let vecsize = Add(bcx, alloc, llsize_of(ccx, ccx.opaque_vec_type));
+
     let {box, body} = base::malloc_unique_dyn(bcx, vecbodyty, vecsize);
-    let boxptr = PointerCast(bcx, box,
-                             T_unique_ptr(T_unique(bcx.ccx(), llvecty)));
-    let bodyptr = PointerCast(bcx, body, T_ptr(llvecty));
-    Store(bcx, fill, GEPi(bcx, bodyptr, [0u, abi::vec_elt_fill]));
-    Store(bcx, alloc, GEPi(bcx, bodyptr, [0u, abi::vec_elt_alloc]));
-    ret {bcx: bcx, val: boxptr};
+    Store(bcx, fill, GEPi(bcx, body, [0u, abi::vec_elt_fill]));
+    Store(bcx, alloc, GEPi(bcx, body, [0u, abi::vec_elt_alloc]));
+    ret {bcx: bcx, val: box};
 }
 
 fn alloc_uniq(bcx: block, unit_ty: ty::t, elts: uint) -> result {
@@ -91,14 +88,9 @@ fn duplicate_uniq(bcx: block, vptr: ValueRef, vec_ty: ty::t) -> result {
     let size = Add(bcx, fill, llsize_of(ccx, ccx.opaque_vec_type));
 
     let unit_ty = ty::sequence_element_type(bcx.tcx(), vec_ty);
-    let llunitty = type_of::type_of(ccx, unit_ty);
-    let llvecty = T_vec(ccx, llunitty);
-    let vecbodyty = unit_ty; // FIXME: This is not the correct type (#2536)
+    let vecbodyty = ty::mk_mut_unboxed_vec(bcx.tcx(), unit_ty);
     let {box: newptr, body: new_body_ptr} =
         base::malloc_unique_dyn(bcx, vecbodyty, size);
-    let newptr = PointerCast(bcx, newptr,
-                             T_unique_ptr(T_unique(bcx.ccx(), llvecty)));
-    let new_body_ptr = PointerCast(bcx, new_body_ptr, T_ptr(llvecty));
     call_memmove(bcx, new_body_ptr, body_ptr, size);
 
     Store(bcx, fill, GEPi(bcx, new_body_ptr, [0u, abi::vec_elt_alloc]));
diff --git a/src/rustc/middle/ty.rs b/src/rustc/middle/ty.rs
index c770e7d71b77769a6d4d7f24e7a1182c297b7d24..8ffc0f36d2039a1a413ae27037ee5c22f38a9a4b 100644
--- a/src/rustc/middle/ty.rs
+++ b/src/rustc/middle/ty.rs
@@ -88,7 +88,7 @@
 export ty_vec, mk_vec, type_is_vec;
 export ty_estr, mk_estr;
 export ty_evec, mk_evec;
-export ty_unboxed_vec, mk_unboxed_vec;
+export ty_unboxed_vec, mk_unboxed_vec, mk_mut_unboxed_vec;
 export vstore, vstore_fixed, vstore_uniq, vstore_box, vstore_slice;
 export ty_nil, mk_nil, type_is_nil;
 export ty_iface, mk_iface;
@@ -677,6 +677,9 @@ fn mk_evec(cx: ctxt, tm: mt, t: vstore) -> t {
 fn mk_unboxed_vec(cx: ctxt, tm: mt) -> t {
     mk_t(cx, ty_unboxed_vec(tm))
 }
+fn mk_mut_unboxed_vec(cx: ctxt, ty: t) -> t {
+    mk_t(cx, ty_unboxed_vec({ty: ty, mutbl: ast::m_imm}))
+}
 
 
 fn mk_rec(cx: ctxt, fs: [field]) -> t { mk_t(cx, ty_rec(fs)) }