diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a73b107..fa5b8d1 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -14,10 +14,7 @@ jobs:
     strategy:
       matrix:
         os:
-          - ubuntu:16.04
-          - ubuntu:18.04
           - ubuntu:20.04
-          - debian:9
           - debian:10
           - debian:11
         nginx_ver: