diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cf385d698f..6f987ffce1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -93,6 +93,7 @@ jobs:
             compiler: clang++-9
             cxxstd: "11,14,17,2a"
             os: ubuntu-20.04
+            install: clang-9
           - toolset: clang
             compiler: clang++-10
             cxxstd: "11,14,17,2a"