diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8c3ab1d..2cf1bf5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -37,6 +37,7 @@ jobs:
           - toolset: gcc-5
             cxxstd: "03,11,14,1z"
             os: ubuntu-18.04
+            install: g++-5
           - toolset: gcc-6
             cxxstd: "03,11,14,1z"
             os: ubuntu-18.04