diff --git a/libraries/build_protobuf.sh b/libraries/build_protobuf.sh
index ee7c7e9..c8978e0 100755
--- a/libraries/build_protobuf.sh
+++ b/libraries/build_protobuf.sh
@@ -1,4 +1,8 @@
 cd protobuf
+if [ -f build/src/.libs/libprotobuf.a ]; then
+	echo "protobuf already builded!"
+	exit 0
+fi
 ./autogen.sh
 cd build
 ../configure