diff --git a/src/rt/rust_builtin.cpp b/src/rt/rust_builtin.cpp
index fb00b07bdfde84abf26c81bad68f073c3f414c3e..9b02256041acc5c7fdab6382e32c5acaf526253b 100644
--- a/src/rt/rust_builtin.cpp
+++ b/src/rt/rust_builtin.cpp
@@ -81,7 +81,6 @@ rust_getcwd() {
     return make_str(task->kernel, cbuf, strlen(cbuf), "rust_str(getcwd");
 }
 
-
 #if defined(__WIN32__)
 extern "C" CDECL rust_vec *
 rust_env_pairs() {
@@ -124,18 +123,6 @@ rust_env_pairs() {
 }
 #endif
 
-// TODO: Allow calling native functions that return double results.
-extern "C" CDECL
-void squareroot(double *input, double *output) {
-    *output = sqrt(*input);
-}
-
-extern "C" CDECL void
-leak(void *thing) {
-    // Do nothing. Call this with move-mode in order to say "Don't worry rust,
-    // I'll take care of this."
-}
-
 extern "C" CDECL intptr_t
 refcount(intptr_t *v) {
     // Passed-in value has refcount 1 too high
@@ -474,13 +461,6 @@ rust_new_task_in_sched(rust_sched_id id) {
     return new_task_common(sched, task);
 }
 
-extern "C" CDECL void
-drop_task(rust_task *target) {
-    if(target) {
-        target->deref();
-    }
-}
-
 extern "C" CDECL void
 rust_task_config_notify(rust_task_id task_id, chan_handle *chan) {
     rust_task *task = rust_task_thread::get_task();
@@ -491,12 +471,6 @@ rust_task_config_notify(rust_task_id task_id, chan_handle *chan) {
     target->deref();
 }
 
-extern "C" CDECL rust_task *
-get_task_pointer(rust_task_id id) {
-    rust_task *task = rust_task_thread::get_task();
-    return task->kernel->get_task_by_id(id);
-}
-
 extern "C" rust_task *
 rust_get_task() {
     return rust_task_thread::get_task();
diff --git a/src/rt/rustrt.def.in b/src/rt/rustrt.def.in
index 6163918ab801523cbef5e4a16b3e6817c057ee71..0a1a6fc913b7c5eab3f9e98449c8d08aa57e7538 100644
--- a/src/rt/rustrt.def.in
+++ b/src/rt/rustrt.def.in
@@ -9,13 +9,10 @@ debug_ptrcast
 debug_tag
 debug_tydesc
 debug_get_stk_seg
-drop_task
 get_port_id
 get_task_id
-get_task_pointer
 get_time
 last_os_error
-leak
 nano_time
 new_port
 new_task
@@ -52,7 +49,6 @@ rust_get_task
 rust_task_config_notify
 sched_threads
 shape_log_str
-squareroot
 start_task
 vec_reserve_shared
 str_reserve_shared