1 files changed, 2 insertions, 2 deletions
diff --git a/ext/digest/digest.c b/ext/digest/digest.c
index 6f9149c31d..d535b35980 100644
--- a/ext/digest/digest.c
+++ b/ext/digest/digest.c
@@ -436,14 +436,14 @@ get_digest_base_metadata(VALUE klass)
     VALUE obj;
     rb_digest_metadata_t *algo;
 
-    for (p = klass; p; p = RCLASS_SUPER(p)) {
+    for (p = klass; !NIL_P(p); p = rb_class_superclass(p)) {
         if (rb_ivar_defined(p, id_metadata)) {
             obj = rb_ivar_get(p, id_metadata);
             break;
         }
     }
 
-    if (!p)
+    if (NIL_P(p))
         rb_raise(rb_eRuntimeError, "Digest::Base cannot be directly inherited in Ruby");
 
     Data_Get_Struct(obj, rb_digest_metadata_t, algo);