diff --git a/lib/rdoc/code_object/top_level.rb b/lib/rdoc/code_object/top_level.rb
index 2bb2767c89..3a6976bbd8 100644
--- a/lib/rdoc/code_object/top_level.rb
+++ b/lib/rdoc/code_object/top_level.rb
@@ -66,7 +66,7 @@ def initialize(absolute_name, relative_name = absolute_name)
 
   def parser=(val)
     @parser = val
-    @store.update_parser_of_file(absolute_name, val) if @store
+    @store.update_parser_of_file(relative_name, val) if @store
     @parser
   end
 
diff --git a/lib/rdoc/store.rb b/lib/rdoc/store.rb
index bcba7ddabb..d91b293142 100644
--- a/lib/rdoc/store.rb
+++ b/lib/rdoc/store.rb
@@ -321,11 +321,11 @@ def resolve_c_superclasses
   end
 
   ##
-  # Sets the parser of +absolute_name+, unless it from a source code file.
+  # Sets the parser of +relative_name+, unless it from a source code file.
 
-  def update_parser_of_file(absolute_name, parser)
-    if top_level = @files_hash[absolute_name] then
-      @text_files_hash[absolute_name] = top_level if top_level.text?
+  def update_parser_of_file(relative_name, parser)
+    if top_level = @files_hash[relative_name] then
+      @text_files_hash[relative_name] = top_level if top_level.text?
     end
   end
 
diff --git a/test/rdoc/rdoc_server_test.rb b/test/rdoc/rdoc_server_test.rb
new file mode 100644
index 0000000000..bc141cabe7
--- /dev/null
+++ b/test/rdoc/rdoc_server_test.rb
@@ -0,0 +1,74 @@
+# frozen_string_literal: true
+require_relative 'support/test_case'
+
+class RDocServerTest < RDoc::TestCase
+
+  def setup
+    super
+
+    @dir = Dir.mktmpdir("test_rdoc_server_")
+
+    File.write File.join(@dir, "PAGE.md"), "# A Page\n\nSome content.\n"
+    File.write File.join(@dir, "NOTES.rdoc"), "= Notes\n\nSome notes.\n"
+    File.write File.join(@dir, "example.rb"), "# A class\nclass Example; end\n"
+
+    @options.files = [@dir]
+    @options.op_dir = File.join(@dir, "_site")
+    @options.root = Pathname(@dir)
+    @options.verbosity = 0
+    @options.finish
+
+    @rdoc.options = @options
+    @rdoc.store = RDoc::Store.new(@options)
+
+    capture_output do
+      @rdoc.parse_files @options.files
+    end
+    @rdoc.store.complete @options.visibility
+
+    @server = RDoc::Server.new(@rdoc, 0)
+  end
+
+  def teardown
+    FileUtils.rm_rf @dir
+    super
+  end
+
+  def test_route_serves_text_page
+    status, content_type, body = @server.send(:route, '/PAGE_md.html')
+
+    assert_equal 200, status
+    assert_equal 'text/html', content_type
+    assert_include body, 'A Page'
+  end
+
+  def test_route_serves_rdoc_text_page
+    status, content_type, body = @server.send(:route, '/NOTES_rdoc.html')
+
+    assert_equal 200, status
+    assert_equal 'text/html', content_type
+    assert_include body, 'Notes'
+  end
+
+  def test_route_serves_class_page
+    status, content_type, body = @server.send(:route, '/Example.html')
+
+    assert_equal 200, status
+    assert_equal 'text/html', content_type
+    assert_include body, 'Example'
+  end
+
+  def test_route_serves_index
+    status, content_type, _body = @server.send(:route, '/')
+
+    assert_equal 200, status
+    assert_equal 'text/html', content_type
+  end
+
+  def test_route_returns_404_for_missing_page
+    status, content_type, _body = @server.send(:route, '/nonexistent.html')
+
+    assert_equal 404, status
+    assert_equal 'text/html', content_type
+  end
+end
diff --git a/test/rdoc/rdoc_store_test.rb b/test/rdoc/rdoc_store_test.rb
index 15492b1fb9..d9bb0bbbdb 100644
--- a/test/rdoc/rdoc_store_test.rb
+++ b/test/rdoc/rdoc_store_test.rb
@@ -348,6 +348,13 @@ def test_find_text_page
     assert_equal page, @store.find_text_page('PAGE.txt')
   end
 
+  def test_find_text_page_when_parser_set_after_add_file
+    page = @store.add_file '/absolute/path/to/PAGE.md', relative_name: 'PAGE.md'
+    page.parser = RDoc::Parser::Simple
+
+    assert_equal page, @store.find_text_page('PAGE.md')
+  end
+
   def test_friendly_path
     @orig_xdg_data_home = ENV.delete('XDG_DATA_HOME')