diff --git a/thread.c b/thread.c
index a5f0e556f1..0a8544fbda 100644
--- a/thread.c
+++ b/thread.c
@@ -321,9 +321,9 @@ rb_thread_s_debug_set(VALUE self, VALUE val)
 #endif
 
 #ifndef fill_thread_id_str
-# define fill_thread_id_string(thid, buf) (void *)(thid)
+# define fill_thread_id_string(thid, buf) ((void *)(uintptr_t)(thid))
 # define fill_thread_id_str(th) (void)0
-# define thread_id_str(th) ((void *)(th)->thread_id)
+# define thread_id_str(th) ((void *)(uintptr_t)(th)->thread_id)
 # define PRI_THREAD_ID "p"
 #endif
 
diff --git a/vm_dump.c b/vm_dump.c
index 15b16a9503..5c1ac81ab4 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -1095,7 +1095,7 @@ rb_vmdebug_stack_dump_all_threads(void)
 	ruby_fill_thread_id_string(th->thread_id, buf);
 	fprintf(stderr, "th: %p, native_id: %s\n", th, buf);
 #else
-	fprintf(stderr, "th: %p, native_id: %p\n", (void *)th, (void *)th->thread_id);
+	fprintf(stderr, "th: %p, native_id: %p\n", (void *)th, (void *)(uintptr_t)th->thread_id);
 #endif
 	rb_vmdebug_stack_dump_raw(th->ec, th->ec->cfp);
     }