diff --git a/lib/opal_hot_reloader/server.rb b/lib/opal_hot_reloader/server.rb
index <HASH>..<HASH> 100644
--- a/lib/opal_hot_reloader/server.rb
+++ b/lib/opal_hot_reloader/server.rb
@@ -65,7 +65,7 @@ module OpalHotReloader
 
 
     def send_updated_file(modified_file)
-      if modified_file =~ /\.rb$/
+      if modified_file =~ /\.rb(\.erb)?$/
         file_contents = File.read(modified_file).force_encoding(Encoding::UTF_8)
         update = {
           type: 'ruby',
Add optional .erb to regex

First step to also watching for ERB file changes.