diff --git a/m6-exercise-files/demos/Grpc/GrpcClient/packages.config b/m6-exercise-files/demos/Grpc/GrpcClient/packages.config
old mode 100755
new mode 100644
index 3d17c6f..a9b9ef9
--- a/m6-exercise-files/demos/Grpc/GrpcClient/packages.config
+++ b/m6-exercise-files/demos/Grpc/GrpcClient/packages.config
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Google.Protobuf" version="3.1.0" targetFramework="net452" />
+  <package id="Google.Protobuf" version="3.15.0" targetFramework="net452" />
   <package id="Grpc" version="1.0.1" targetFramework="net452" />
   <package id="Grpc.Core" version="1.0.1" targetFramework="net452" />
   <package id="System.Interactive.Async" version="3.0.0" targetFramework="net452" />