diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 2964cd3..2163fe0 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -8,7 +8,7 @@ on:
 jobs:
   p3_7:
     name: Python 3.7.1
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
         with:
@@ -24,7 +24,7 @@ jobs:
 
   p3_8:
     name: Python 3.8.0
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
         with:
@@ -40,7 +40,7 @@ jobs:
 
   p3_9:
     name: Python 3.9.0
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
         with:
@@ -56,7 +56,7 @@ jobs:
 
   p3_10:
     name: Python 3.10.0
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
         with:
@@ -72,7 +72,7 @@ jobs:
 
   p3_11:
     name: Python 3.11.0
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2
         with: