diff --git a/lib/rdoc/erb_partial.rb b/lib/rdoc/erb_partial.rb
index 8dc2c46013..d6e3f41b7e 100644
--- a/lib/rdoc/erb_partial.rb
+++ b/lib/rdoc/erb_partial.rb
@@ -12,7 +12,7 @@ class RDoc::ERBPartial < ERB
   def set_eoutvar compiler, eoutvar = '_erbout'
     super
 
-    compiler.pre_cmd = ["#{eoutvar} ||= ''"]
+    compiler.pre_cmd = ["#{eoutvar} ||= +''"]
   end
 
 end
diff --git a/test/test_rdoc_generator_darkfish.rb b/test/test_rdoc_generator_darkfish.rb
index edabe4fad4..1b7bca0890 100644
--- a/test/test_rdoc_generator_darkfish.rb
+++ b/test/test_rdoc_generator_darkfish.rb
@@ -202,6 +202,13 @@ def test_template_for_partial
     assert_same template, @g.send(:template_for, partial)
   end
 
+  def test_erb_partial_with_frozen_string_literal
+    erb = RDoc::ERBPartial.new('<%= "ruby/rdoc#683" %>')
+    # It's the same behavior of RUBYOPT=--enable=frozen-string-literal.
+    result = eval("# frozen_string_literal: true\n#{erb.src}")
+    assert_kind_of String, result
+  end
+
   def test_generated_method_with_html_tag_yield
     top_level = @store.add_file 'file.rb'
     top_level.add_class @klass.class, @klass.name