Add dependency to ply package
diff --git a/setup.py b/setup.py
index 31ba1bb..0313e81 100644
--- a/setup.py
+++ b/setup.py
@@ -8,4 +8,5 @@
       author='Dusan Klinec',
       url='https://github.com/sb98052/plyprotobuf',
       packages=['plyproto'],
+      install_requires=['ply']
      )