diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index f68bf3d..d4d1372 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -135,6 +135,8 @@ if(MSVC)
   # warning is not important since those members do not need to be interfaced
   # with.
   set_source_files_properties(${gen_sources} COMPILE_FLAGS "/wd4251 /wd4146")
+  # Fix for protobuf 3.12 - allow big object files
+  add_definitions(/bigobj)
 endif()
 
 set_source_files_properties(${gen_headers} ${gen_sources} ${gen_ruby_scripts}