diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index d2ac316..ca6b4d9 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -9,10 +9,13 @@ jobs:
       matrix:
         # g++-4.8 and 4.9 are tested on Travis.CI.
         compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
-        standard: ['11', '14', '17']
+        standard: ['11', '14', '17', '20']
         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
         uses: actions/checkout@v2
@@ -47,11 +50,14 @@ jobs:
     strategy:
       matrix:
         compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
-        standard: ['11', '14', '17']
+        standard: ['11', '14', '17', '20']
         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'}
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -81,7 +87,7 @@ jobs:
     runs-on: windows-2019
     strategy:
       matrix:
-        standard: ['11', '14', '17']
+        standard: ['11', '14', '17', '20']
         config: ['Release', 'Debug']
     steps:
       - name: Checkout