diff --git a/docs/building-cmake.md b/docs/building-cmake.md
index de1560a383..e414d76fd2 100644
--- a/docs/building-cmake.md
+++ b/docs/building-cmake.md
@@ -19,6 +19,7 @@ You will need GCC 7.2 and CMake 3.2 installed. To install them and all the requi
     sudo apt-get install gcc-7 g++-7 cmake
     sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-7 60
     sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-7 60
+    sudo update-alternatives --config gcc
     sudo add-apt-repository --remove ppa:ubuntu-toolchain-r/test
     sudo add-apt-repository --remove ppa:george-edison55/cmake-3.x