diff --git a/lib/webpacker/compiler.rb b/lib/webpacker/compiler.rb
index d9ead0780..348c32833 100644
--- a/lib/webpacker/compiler.rb
+++ b/lib/webpacker/compiler.rb
@@ -45,11 +45,7 @@ def last_compilation_digest
 
     def watched_files_digest
       files = Dir[*default_watched_paths, *watched_paths].reject { |f| File.directory?(f) }
-      file_ids = if ENV["CI"]
-        files.sort.map { |f| "#{File.basename(f)}/#{Digest::SHA1.file(f).hexdigest}" }
-      else
-        files.map { |f| "#{File.basename(f)}/#{File.mtime(f).utc.to_i}" }
-      end
+      file_ids = files.sort.map { |f| "#{File.basename(f)}/#{Digest::SHA1.file(f).hexdigest}" }
       Digest::SHA1.hexdigest(file_ids.join("/"))
     end