diff --git a/src/libcore/str.rs b/src/libcore/str.rs
index 7e5778f04454..888d992321cd 100644
--- a/src/libcore/str.rs
+++ b/src/libcore/str.rs
@@ -115,11 +115,6 @@ export
    StrSlice,
    UniqueStr;
 
-#[abi = "cdecl"]
-extern mod rustrt {
-    fn str_reserve_shared(&ss: ~str, nn: libc::size_t);
-}
-
 /*
 Section: Creating a string
 */
@@ -1818,8 +1813,9 @@ pure fn as_buf<T>(s: &str, f: fn(*u8, uint) -> T) -> T {
  * * n - The number of bytes to reserve space for
  */
 fn reserve(&s: ~str, n: uint) {
-    if capacity(s) < n {
-        rustrt::str_reserve_shared(s, n as size_t);
+    unsafe {
+        let v: *mut ~[u8] = ::unsafe::reinterpret_cast(ptr::addr_of(s));
+        vec::reserve(*v, n + 1);
     }
 }
 
diff --git a/src/rt/rust_builtin.cpp b/src/rt/rust_builtin.cpp
index a662141bf628..f9da1c91cf0d 100644
--- a/src/rt/rust_builtin.cpp
+++ b/src/rt/rust_builtin.cpp
@@ -141,13 +141,6 @@ vec_reserve_shared(type_desc* ty, rust_vec_box** vp,
     reserve_vec_exact(task, vp, n_elts * ty->size);
 }
 
-extern "C" CDECL void
-str_reserve_shared(rust_vec_box** sp,
-                   size_t n_elts) {
-    rust_task *task = rust_get_current_task();
-    reserve_vec_exact(task, sp, n_elts + 1);
-}
-
 extern "C" CDECL rust_vec*
 rand_seed() {
     size_t size = sizeof(ub4) * RANDSIZ;
diff --git a/src/rt/rustrt.def.in b/src/rt/rustrt.def.in
index 191ebe6f0bea..8c550833d1c3 100644
--- a/src/rt/rustrt.def.in
+++ b/src/rt/rustrt.def.in
@@ -61,7 +61,6 @@ shape_log_str
 start_task
 vec_reserve_shared_actual
 vec_reserve_shared
-str_reserve_shared
 task_clear_event_reject
 task_wait_event
 task_signal_event