diff --git a/bignum.c b/bignum.c
index 3767485..95a2504 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1710,7 +1710,7 @@ rb_big_eq(VALUE x, VALUE y)
  *     68719476736.eql?(68719476736.0)   #=> false
  */
 
-static VALUE
+VALUE
 rb_big_eql(VALUE x, VALUE y)
 {
     if (!RB_TYPE_P(y, T_BIGNUM)) return Qfalse;
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index 6b8cfc1..5ff17a4 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -124,6 +124,7 @@ VALUE rb_dbl2big(double);
 double rb_big2dbl(VALUE);
 VALUE rb_big_cmp(VALUE, VALUE);
 VALUE rb_big_eq(VALUE, VALUE);
+VALUE rb_big_eql(VALUE, VALUE);
 VALUE rb_big_plus(VALUE, VALUE);
 VALUE rb_big_minus(VALUE, VALUE);
 VALUE rb_big_mul(VALUE, VALUE);
diff --git a/thread.c b/thread.c
index 3a2f0d8..51199e9 100644
--- a/thread.c
+++ b/thread.c
@@ -4598,7 +4598,7 @@ recursive_list_access(void)
 }
 
 /*
- * Returns Qtrue iff obj_id (or the pair <obj, paired_obj>) is already
+ * Returns Qtrue if obj_id (or the pair <obj, paired_obj>) is already
  * in the recursion list.
  * Assumes the recursion list is valid.
  */
@@ -4606,17 +4606,24 @@ recursive_list_access(void)
 static VALUE
 recursive_check(VALUE list, VALUE obj_id, VALUE paired_obj_id)
 {
+#if SIZEOF_LONG == SIZEOF_VOIDP
+  #define OBJ_ID_EQL(obj_id, other) ((obj_id) == (other))
+#elif SIZEOF_LONG_LONG == SIZEOF_VOIDP
+  #define OBJ_ID_EQL(obj_id, other) (RB_TYPE_P((obj_id), T_BIGNUM) ? \
+    rb_big_eql((obj_id), (other)) : ((obj_id) == (other)))
+#endif
+
     VALUE pair_list = rb_hash_lookup2(list, obj_id, Qundef);
     if (pair_list == Qundef)
 	return Qfalse;
     if (paired_obj_id) {
 	if (!RB_TYPE_P(pair_list, T_HASH)) {
-	if (pair_list != paired_obj_id)
-	    return Qfalse;
+	    if (!OBJ_ID_EQL(paired_obj_id, pair_list))
+		return Qfalse;
 	}
 	else {
-	if (NIL_P(rb_hash_lookup(pair_list, paired_obj_id)))
-	    return Qfalse;
+	    if (NIL_P(rb_hash_lookup(pair_list, paired_obj_id)))
+		return Qfalse;
 	}
     }
     return Qtrue;