diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 70085f5c..961c934f 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -28,6 +28,11 @@ jobs:
             std: 17
             install: sudo apt install g++-8
             os: ubuntu-18.04
+          - cxx: g++-9
+            build_type: Debug
+            std: 17
+            install: sudo apt install g++-9
+            os: ubuntu-18.04
           - cxx: g++-10
             build_type: Debug
             std: 17