make protobuf building consistent
diff --git a/vsprojects/build_plugins.bat b/vsprojects/build_plugins.bat
index 7c8e056..ae5c5f0 100644
--- a/vsprojects/build_plugins.bat
+++ b/vsprojects/build_plugins.bat
@@ -38,7 +38,7 @@
 @call "%VS120COMNTOOLS%\..\..\vc\vcvarsall.bat" x86
 
 @rem Build third_party/protobuf
-msbuild ..\third_party\protobuf\cmake\protobuf.sln /p:Configuration=Release || goto :error
+msbuild ..\third_party\protobuf\cmake\build\solution\protobuf.sln /p:Configuration=Release || goto :error
 
 @rem Build the C# protoc plugins
 msbuild grpc_protoc_plugins.sln /p:Configuration=Release || goto :error