diff --git a/lib/mini_racer/truffleruby.rb b/lib/mini_racer/truffleruby.rb
index cc9c3fe..5beed70 100644
--- a/lib/mini_racer/truffleruby.rb
+++ b/lib/mini_racer/truffleruby.rb
@@ -249,7 +249,7 @@ def convert_js_to_ruby(value)
         elsif map?(value)
           js_map_to_hash(value)
         elsif map_iterator?(value)
-          value.flat_map { |e| convert_js_to_ruby(e) }
+          value.map { |e| convert_js_to_ruby(e) }
         else
           object = value
           h = {}
diff --git a/test/mini_racer_test.rb b/test/mini_racer_test.rb
index 3dbc336..87dcc00 100644
--- a/test/mini_racer_test.rb
+++ b/test/mini_racer_test.rb
@@ -1063,8 +1063,17 @@ def test_map
     context = MiniRacer::Context.new
     expected = {"x" => 42, "y" => 43}
     assert_equal expected, context.eval("new Map([['x', 42], ['y', 43]])")
-    expected = ["x", 42, "y", 43]
+    if RUBY_ENGINE == "truffleruby"
+      # See https://github.com/rubyjs/mini_racer/pull/325#discussion_r1907187166
+      expected = [["x", 42], ["y", 43]]
+    else
+      expected = ["x", 42, "y", 43]
+    end
     assert_equal expected, context.eval("new Map([['x', 42], ['y', 43]]).entries()")
+    expected = ["x", "y"]
+    assert_equal expected, context.eval("new Map([['x', 42], ['y', 43]]).keys()")
+    expected = [[42], [43]]
+    assert_equal expected, context.eval("new Map([['x', [42]], ['y', [43]]]).values()")
   end
 
   def test_regexp_string_iterator