diff --git a/.github/workflows/basic.yml b/.github/workflows/basic.yml
index 884634f2dd66e5eaf6d4aa45e2897fd121fd2674..d1c7f06f3d59d6184b180b860faafa600774749c 100644
--- a/.github/workflows/basic.yml
+++ b/.github/workflows/basic.yml
@@ -15,7 +15,7 @@ jobs:
         os:    ["ubuntu-20.04"]
         cxx:   ["g++"]
         cc:    ["gcc"]
-        ver:   ["9"]
+        ver:   ["8"]
         py:    ["3.6"]
         cmake: ["3.12.x"]
         mpi:   ["ON"]