diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0dadb25..b64f8af 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -7,15 +7,10 @@ jobs:
     runs-on: Ubuntu-20.04
     strategy:
       matrix:
-        # g++-4.8 and 4.9 are tested on Travis.CI.
-        compiler: ['g++-11', 'g++-10', 'g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
+        compiler: ['g++-11', 'g++-10', 'g++-9', 'g++-8', 'g++-7']
         standard: ['11', '14', '17', '20']
         unreleased: ['ON', 'OFF']
         exclude:
-            - {compiler: 'g++-5', standard: '17'}
-            - {compiler: 'g++-6', standard: '17'}
-            - {compiler: 'g++-5', standard: '20'}
-            - {compiler: 'g++-6', standard: '20'}
             - {compiler: 'g++-7', standard: '20'}
     steps:
       - name: Checkout
@@ -24,11 +19,9 @@ jobs:
           submodules: true
       - name: Install
         run: |
-            sudo apt-add-repository ppa:mhier/libboost-latest
-            sudo apt-get update
-            sudo apt-get install boost1.70
             sudo apt-add-repository ppa:ubuntu-toolchain-r/test
             sudo apt-get update
+            sudo apt-get install libboost-test-dev
             sudo apt-get install ${{ matrix.compiler }}
       - name: Configure
         run: |
@@ -48,16 +41,10 @@ jobs:
     runs-on: Ubuntu-20.04
     strategy:
       matrix:
-        compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
+        compiler: ['12', '11', '10', '9', '8', '7', '6.0']
         standard: ['11', '14', '17', '20']
         unreleased: ['ON', 'OFF']
         exclude:
-            - {compiler: '3.9', standard: '17'}
-            - {compiler: '4.0', standard: '17'}
-            - {compiler: '5.0', standard: '17'}
-            - {compiler: '3.9', standard: '20'}
-            - {compiler: '4.0', standard: '20'}
-            - {compiler: '5.0', standard: '20'}
             - {compiler: '6.0', standard: '20'}
             - {compiler: '7',   standard: '20'}
             - {compiler: '8',   standard: '20'}
@@ -69,11 +56,9 @@ jobs:
           submodules: true
       - name: Install
         run: |
-            sudo apt-add-repository ppa:mhier/libboost-latest
-            sudo apt-get update
-            sudo apt-get install boost1.70
             sudo apt-add-repository ppa:ubuntu-toolchain-r/test
             sudo apt-get update
+            sudo apt-get install libboost-test-dev
             sudo apt-get install clang-${{ matrix.compiler }}
       - name: Configure
         run: |