add protobuf build
diff --git a/Makefile.am b/Makefile.am
index d39bda2..1779f49 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3,7 +3,10 @@
 
 all: grpc-c
 
-protobuf-c:
+protobuf:
+	cd third_party/protobuf; ./autogen.sh; ./configure; make; sudo make install
+
+protobuf-c: protobuf
 	cd third_party/protobuf-c; ./autogen.sh; ./configure; make; sudo make install
 
 grpc: