diff --git a/src/julia_internal.h b/src/julia_internal.h
index c6c9f3f8e21df..d6a7e95f982ca 100644
--- a/src/julia_internal.h
+++ b/src/julia_internal.h
@@ -338,7 +338,6 @@ void *jl_gc_perm_alloc_nolock(size_t sz, int zero,
     unsigned align, unsigned offset) JL_NOTSAFEPOINT;
 void *jl_gc_perm_alloc(size_t sz, int zero,
     unsigned align, unsigned offset) JL_NOTSAFEPOINT;
-void jl_gc_force_mark_old(jl_ptls_t ptls, jl_value_t *v);
 void gc_sweep_sysimg(void);