diff --git a/src/rt/rust_task_thread.cpp b/src/rt/rust_task_thread.cpp
index dde16ad70bd..a83f890d62b 100644
--- a/src/rt/rust_task_thread.cpp
+++ b/src/rt/rust_task_thread.cpp
@@ -371,7 +371,6 @@ rust_task_thread::prepare_c_stack(rust_task *task) {
     I(this, !extra_c_stack);
     if (!cached_c_stack && !task->have_c_stack()) {
         cached_c_stack = create_stack(kernel, C_STACK_SIZE);
-        prepare_valgrind_stack(cached_c_stack);
     }
 }
 
diff --git a/src/rt/rust_task_thread.h b/src/rt/rust_task_thread.h
index 58ae8aa12f5..f82a20a70a2 100644
--- a/src/rt/rust_task_thread.h
+++ b/src/rt/rust_task_thread.h
@@ -189,6 +189,7 @@ rust_task_thread::borrow_c_stack() {
         your_stack = cached_c_stack;
         cached_c_stack = NULL;
     }
+    prepare_valgrind_stack(your_stack);
     return your_stack;
 }