diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0baefcf8b..0a813ad30 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -332,7 +332,7 @@ set(GNSSSDR_GNSS_SIM_LOCAL_VERSION "master")
 set(GNSSSDR_GPSTK_LOCAL_VERSION "8.0.0")
 set(GNSSSDR_MATIO_LOCAL_VERSION "1.5.23")
 set(GNSSSDR_PUGIXML_LOCAL_VERSION "1.12")
-set(GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION "3.20.1")
+set(GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION "21.1")
 set(GNSSSDR_BENCHMARK_LOCAL_VERSION "1.6.1")
 set(GNSSSDR_MATHJAX_EXTERNAL_VERSION "2.7.7")
 
diff --git a/README.md b/README.md
index 4eebe1323..d64cf0de0 100644
--- a/README.md
+++ b/README.md
@@ -496,16 +496,19 @@ $ sudo apt-get install autoconf automake libtool curl make g++ unzip
 and then:
 
 ```
-$ wget https://github.com/protocolbuffers/protobuf/releases/download/v3.20.1/protobuf-cpp-3.20.1.tar.gz
-$ tar xvfz protobuf-cpp-3.20.1.tar.gz
-$ cd protobuf-3.20.1
+$ git clone https://github.com/protocolbuffers/protobuf.git
+$ cd protobuf
+$ git submodule update --init --recursive
 $ ./autogen.sh
-$ ./configure
-$ make
+$ /configure
+$ make -j$(nproc)
 $ sudo make install
 $ sudo ldconfig
 ```
 
+For more options, please check the
+[Protocol Buffers' installation instructions](https://github.com/protocolbuffers/protobuf/blob/main/src/README.md/).
+
 #### Install [Pugixml](https://pugixml.org/ "Pugixml's Homepage"), a light-weight C++ XML processing library:
 
 ```