diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 664fc99..29bc0ad 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,6 +7,11 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          # Ruby 2.5.x
+          - ruby: 2.5
+            gemfile: "gemfiles/Gemfile.rails-4.2.x"
+          - ruby: 2.5
+            gemfile: "gemfiles/Gemfile.rails-4.2.x.sprockets-4.x"
           # Ruby 2.6.x
           - ruby: 2.6
             gemfile: "gemfiles/Gemfile.rails-4.2.x"