diff --git a/lib/cgi/escape.rb b/lib/cgi/escape.rb
index 6d84773..6748198 100644
--- a/lib/cgi/escape.rb
+++ b/lib/cgi/escape.rb
@@ -160,13 +160,6 @@ def unescapeHTML(string)
     string.force_encoding enc
   end
 
-  # Synonym for CGI.escapeHTML(str)
-  alias escape_html escapeHTML
-  alias h escapeHTML
-
-  # Synonym for CGI.unescapeHTML(str)
-  alias unescape_html unescapeHTML
-
   # TruffleRuby runs the pure-Ruby variant faster, do not use the C extension there
   unless RUBY_ENGINE == 'truffleruby'
     begin
@@ -175,6 +168,14 @@ def unescapeHTML(string)
     end
   end
 
+  # Aliases must be defined on EscapeExt so they resolve to the C methods.
+  target = defined?(CGI::EscapeExt) && CGI::EscapeExt.method_defined?(:escapeHTML) ? CGI::EscapeExt : self
+  target.module_eval do
+    alias escape_html escapeHTML
+    alias h escapeHTML
+    alias unescape_html unescapeHTML
+  end
+
   # Escape only the tags of certain HTML elements in +string+.
   #
   # Takes an element or elements or array of elements.  Each element
diff --git a/test/cgi/test_cgi_escape.rb b/test/cgi/test_cgi_escape.rb
index 73d99e8..4bf0d45 100644
--- a/test/cgi/test_cgi_escape.rb
+++ b/test/cgi/test_cgi_escape.rb
@@ -293,6 +293,39 @@ def test_cgi_unescapeElement
   end
 end
 
+class CGIEscapeNativeExtTest < Test::Unit::TestCase
+  def test_escape_html_uses_native_implementation
+    omit "C extension not available" unless defined?(CGI::EscapeExt) && CGI::EscapeExt.method_defined?(:escapeHTML)
+    assert_equal CGI::EscapeExt, CGI.method(:escape_html).owner
+    assert_equal CGI::EscapeExt, CGI.method(:h).owner
+    assert_equal CGI::EscapeExt, CGI.method(:unescape_html).owner
+  end
+
+  def test_escape_html_allocates_same_as_escapeHTML
+    omit "C extension not available" unless defined?(CGI::EscapeExt) && CGI::EscapeExt.method_defined?(:escapeHTML)
+
+    input = "'&\"<>hello world"
+    n = 100
+
+    # Warm up
+    2.times { n.times { CGI.escapeHTML(input) } }
+    2.times { n.times { CGI.escape_html(input) } }
+
+    GC.disable
+    before = GC.stat(:total_allocated_objects)
+    n.times { CGI.escapeHTML(input) }
+    camel_allocs = GC.stat(:total_allocated_objects) - before
+
+    before = GC.stat(:total_allocated_objects)
+    n.times { CGI.escape_html(input) }
+    snake_allocs = GC.stat(:total_allocated_objects) - before
+    GC.enable
+
+    assert_equal camel_allocs, snake_allocs,
+      "escape_html allocated #{snake_allocs} objects vs escapeHTML #{camel_allocs} — alias may not be using the C extension"
+  end
+end
+
 class CGIEscapePureRubyTest < Test::Unit::TestCase
   def setup
     CGI::EscapeExt.module_eval do