diff --git a/services/tunnelbroker/CMakeLists.txt b/services/tunnelbroker/CMakeLists.txt
--- a/services/tunnelbroker/CMakeLists.txt
+++ b/services/tunnelbroker/CMakeLists.txt
@@ -43,12 +43,12 @@
 set(GENERATED_CODE_DIR "${GENERATED_BASE_DIR}/_generated")
 file(MAKE_DIRECTORY ${GENERATED_CODE_DIR})
 
-set(proto_srcs "${GENERATED_CODE_DIR}/tunnelbroker.pb.cc")
-set(proto_hdrs "${GENERATED_CODE_DIR}/tunnelbroker.pb.h")
-set(grpc_srcs "${GENERATED_CODE_DIR}/tunnelbroker.grpc.pb.cc")
-set(grpc_hdrs "${GENERATED_CODE_DIR}/tunnelbroker.grpc.pb.h")
+set(_proto_srcs "${GENERATED_CODE_DIR}/tunnelbroker.pb.cc")
+set(_proto_hdrs "${GENERATED_CODE_DIR}/tunnelbroker.pb.h")
+set(_grpc_srcs "${GENERATED_CODE_DIR}/tunnelbroker.grpc.pb.cc")
+set(_grpc_hdrs "${GENERATED_CODE_DIR}/tunnelbroker.grpc.pb.h")
 add_custom_command(
-  OUTPUT "${proto_srcs}" "${proto_hdrs}" "${grpc_srcs}" "${grpc_hdrs}"
+  OUTPUT "${_proto_srcs}" "${_proto_hdrs}" "${_grpc_srcs}" "${_grpc_hdrs}"
   COMMAND ${_PROTOBUF_PROTOC}
   ARGS --grpc_out "${GENERATED_CODE_DIR}"
   --cpp_out "${GENERATED_CODE_DIR}"
@@ -56,6 +56,7 @@
   --plugin=protoc-gen-grpc="${_GRPC_CPP_PLUGIN_EXECUTABLE}"
   "${proto}"
   DEPENDS "${proto}"
+  COMMENT "Generate protobuf files"
 )
 
 file(GLOB_RECURSE SOURCE_CODE "./src/*.cpp")