diff --git a/iseq.c b/iseq.c
index 93e58db2e65..f2db484f59f 100644
--- a/iseq.c
+++ b/iseq.c
@@ -3002,6 +3002,10 @@ rb_iseq_disasm_recursive(const rb_iseq_t *iseq, VALUE indent)
         n += rb_iseq_disasm_insn(str, code, n, iseq, child);
     }
 
+    if (body->mandatory_only_iseq) {
+        rb_ary_push(child, (VALUE)body->mandatory_only_iseq);
+    }
+
     for (l = 0; l < RARRAY_LEN(child); l++) {
         VALUE isv = rb_ary_entry(child, l);
         if (done_iseq && st_is_member(done_iseq, (st_data_t)isv)) continue;
diff --git a/test/ruby/test_iseq.rb b/test/ruby/test_iseq.rb
index 30931587f8b..0a06d01b08a 100644
--- a/test/ruby/test_iseq.rb
+++ b/test/ruby/test_iseq.rb
@@ -524,6 +524,12 @@ class TestISeq < Test::Unit::TestCase
     assert_equal [:&], param_names
   end
 
+  def test_disasm_mandatory_only_overloaded
+    disasm = RubyVM::InstructionSequence.disasm(Time.method(:at))
+    assert_include disasm, "<builtin!time_s_at1/1>"
+    assert_include disasm, "<builtin!time_s_at/4>"
+  end
+
   def strip_lineno(source)
     source.gsub(/^.*?: /, "")
   end