diff --git a/.github/workflows/cpp_ubuntu20_04.yml b/.github/workflows/cpp_ubuntu20_04.yml
index 47e5d0d..8939296 100644
--- a/.github/workflows/cpp_ubuntu20_04.yml
+++ b/.github/workflows/cpp_ubuntu20_04.yml
@@ -29,6 +29,10 @@ jobs:
     - name: Install newest git version
       run: sudo apt update && sudo apt-get install -y software-properties-common && sudo add-apt-repository -y ppa:git-core/ppa && sudo apt-get update && sudo apt-get install -y git
 
+    - name: Add testing repository
+      run: sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y && sudo apt update
+      if: ${{ matrix.gcc }} == '12'
+
     - name: Install GCC version ${{ matrix.gcc }}
       run: sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y && sudo apt update && sudo apt install -y gcc-${{ matrix.gcc }} g++-${{ matrix.gcc }} && sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-${{ matrix.gcc }} 100 --slave /usr/bin/g++ g++ /usr/bin/g++-${{ matrix.gcc }}