diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 1cf65ad..8539514 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,6 +13,9 @@ jobs:
           - "2.6"
           - "2.7"
           - "3.0"
+          - "3.1"
+          - "3.2"
+          - "3.3"
     steps:
       - uses: actions/checkout@v4
       - name: Set up Groonga APT repository
diff --git a/groonga-query-log.gemspec b/groonga-query-log.gemspec
index 3c52eb8..bd07321 100644
--- a/groonga-query-log.gemspec
+++ b/groonga-query-log.gemspec
@@ -54,6 +54,7 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency("charty")
   spec.add_runtime_dependency("diff-lcs")
+  spec.add_runtime_dependency("net-smtp")
   spec.add_runtime_dependency("groonga-client", ">= 0.6.2")
   spec.add_runtime_dependency("groonga-log", ">= 0.1.2")