diff --git a/lib/modules/spectrogram.rb b/lib/modules/spectrogram.rb
index a4884f95..f23729f5 100644
--- a/lib/modules/spectrogram.rb
+++ b/lib/modules/spectrogram.rb
@@ -1,4 +1,5 @@
 require 'OS'
+require 'open3'
 
 module Spectrogram
   @sox_path = if OS.windows? then "./vendor/bin/sox/windows/sox.exe" else "sox" end