diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 49efaba..2285b75 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -108,7 +108,7 @@ jobs:
             cxxstd: "03,11,14,17,2a"
             os: ubuntu-18.04
             install: clang-8
-            gcc_toolchain: 9
+            gcc_toolchain: 7
           - toolset: clang
             compiler: clang++-9
             cxxstd: "03,11,14,17,2a"