diff --git a/src/rt/rustrt.def.in b/src/rt/rustrt.def.in
index f51d4c502b04..7977c42cfa48 100644
--- a/src/rt/rustrt.def.in
+++ b/src/rt/rustrt.def.in
@@ -73,6 +73,7 @@ upcall_free
 upcall_validate_box
 upcall_log_type
 upcall_malloc
+upcall_malloc_dyn
 upcall_rust_personality
 upcall_vec_grow
 upcall_str_new