diff --git a/.github/workflows/all.yml b/.github/workflows/all.yml
index e0683f50..0667f5b1 100644
--- a/.github/workflows/all.yml
+++ b/.github/workflows/all.yml
@@ -18,7 +18,7 @@ jobs:
 
     strategy:
       matrix:
-        os: [ubuntu-latest]
+        os: [ubuntu-20.04]
 #       os: [ubuntu-latest, macos-latest] # @todo: macOS need fixes
 
     steps:
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b223eb4d..30a7476b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -17,7 +17,7 @@ jobs:
     strategy:
       matrix:
         compiler: [gcc, clang]
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-20.04, macos-latest, windows-latest]
         exclude:
            - os: macos-latest
              compiler: gcc
diff --git a/.github/workflows/ccheck.yml b/.github/workflows/ccheck.yml
index 17836868..82ad620a 100644
--- a/.github/workflows/ccheck.yml
+++ b/.github/workflows/ccheck.yml
@@ -5,7 +5,7 @@ on: [push, pull_request]
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     steps:
     - uses: actions/checkout@v3