diff --git a/cont.c b/cont.c
index d98326db6b..6387118f4a 100644
--- a/cont.c
+++ b/cont.c
@@ -250,7 +250,7 @@ fiber_status_set(rb_fiber_t *fib, enum fiber_status s)
 }
 
 void
-ec_set_vm_stack(rb_execution_context_t *ec, VALUE *stack, size_t size)
+rb_ec_set_vm_stack(rb_execution_context_t *ec, VALUE *stack, size_t size)
 {
     ec->vm_stack = stack;
     ec->vm_stack_size = size;
@@ -673,7 +673,7 @@ cont_capture(volatile int *volatile stat)
     cont->saved_vm_stack.ptr = ALLOC_N(VALUE, ec->vm_stack_size);
     MEMCPY(cont->saved_vm_stack.ptr, ec->vm_stack, VALUE, ec->vm_stack_size);
 #endif
-    ec_set_vm_stack(&cont->saved_ec, NULL, 0);
+    rb_ec_set_vm_stack(&cont->saved_ec, NULL, 0);
     cont_save_machine_stack(th, cont);
 
     /* backup ensure_list to array for search in another context */
@@ -1425,7 +1425,7 @@ fiber_init(VALUE fibval, VALUE proc)
     else {
         vm_stack = ruby_xmalloc(fib_stack_bytes);
     }
-    ec_set_vm_stack(sec, vm_stack, fib_stack_bytes / sizeof(VALUE));
+    rb_ec_set_vm_stack(sec, vm_stack, fib_stack_bytes / sizeof(VALUE));
     sec->cfp = (void *)(sec->vm_stack + sec->vm_stack_size);
 
     rb_vm_push_frame(sec,
@@ -1777,7 +1777,7 @@ rb_fiber_close(rb_fiber_t *fib)
     else {
         ruby_xfree(vm_stack);
     }
-    ec_set_vm_stack(ec, NULL, 0);
+    rb_ec_set_vm_stack(ec, NULL, 0);
 
 #if !FIBER_USE_NATIVE
     /* should not mark machine stack any more */
diff --git a/vm.c b/vm.c
index c63c773194..a10fff640b 100644
--- a/vm.c
+++ b/vm.c
@@ -2557,7 +2557,7 @@ th_init(rb_thread_t *th, VALUE self)
 	/* vm_stack_size is word number.
 	 * th->vm->default_params.thread_vm_stack_size is byte size. */
 	size_t size = th->vm->default_params.thread_vm_stack_size / sizeof(VALUE);
-	ec_set_vm_stack(th->ec, rb_thread_recycle_stack(size), size);
+	rb_ec_set_vm_stack(th->ec, rb_thread_recycle_stack(size), size);
     }
 
     th->ec->cfp = (void *)(th->ec->vm_stack + th->ec->vm_stack_size);
diff --git a/vm_core.h b/vm_core.h
index 6b094dcbfb..7a89dd019c 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -880,7 +880,7 @@ typedef struct rb_execution_context_struct {
     } machine;
 } rb_execution_context_t;
 
-void ec_set_vm_stack(rb_execution_context_t *ec, VALUE *stack, size_t size);
+void rb_ec_set_vm_stack(rb_execution_context_t *ec, VALUE *stack, size_t size);
 
 typedef struct rb_thread_struct {
     struct list_node vmlt_node;