diff --git a/src/rt/memory_region.h b/src/rt/memory_region.h
index 4caecb3cd5df..1a3e94c10bd1 100644
--- a/src/rt/memory_region.h
+++ b/src/rt/memory_region.h
@@ -15,7 +15,7 @@
 //
 // 0 --- no headers, no debugging support
 // 1 --- support poison, but do not track allocations
-// 2 --- track allocations in deatil
+// 2 --- track allocations in detail
 //
 // NB: please do not commit code with level 2. It's
 // hugely expensive and should only be used as a last resort.
diff --git a/src/rt/rust_upcall.cpp b/src/rt/rust_upcall.cpp
index 754a1f2d1895..ddf490f6dba2 100644
--- a/src/rt/rust_upcall.cpp
+++ b/src/rt/rust_upcall.cpp
@@ -224,7 +224,7 @@ void upcall_s_clone_type_desc(s_clone_type_desc_args *args)
  * Called to deep-clone type descriptors so they can be attached to a sendable
  * function.  Eventually this should perhaps move to a centralized hashtable.
  */
-type_desc *
+extern "C" CDECL type_desc *
 upcall_clone_type_desc(type_desc *td) {
     s_clone_type_desc_args args = { td, 0 };
     SWITCH_STACK(&args, upcall_s_clone_type_desc);
diff --git a/src/rt/rustrt.def.in b/src/rt/rustrt.def.in
index 306c750c8fbb..a29941169cb5 100644
--- a/src/rt/rustrt.def.in
+++ b/src/rt/rustrt.def.in
@@ -58,6 +58,7 @@ upcall_dynastack_free
 upcall_dynastack_mark
 upcall_fail
 upcall_free
+upcall_clone_type_desc
 upcall_get_type_desc
 upcall_log_type
 upcall_malloc