diff --git a/ext/dl/cptr.c b/ext/dl/cptr.c
index b3d7ef954a..edaa2e66bd 100644
--- a/ext/dl/cptr.c
+++ b/ext/dl/cptr.c
@@ -388,7 +388,6 @@ static VALUE
 rb_dlptr_inspect(VALUE self)
 {
     struct ptr_data *data;
-    char str[1024];
 
     TypedData_Get_Struct(self, struct ptr_data, &dlptr_data_type, data);
     return rb_sprintf("#<%"PRIsVALUE":%p ptr=%p size=%ld free=%p>",