diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b1700f2ded12..5ba0da7f9573 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -44,7 +44,7 @@ jobs:
           - os: ubuntu-latest
             ruby: "4.0"
             # (b/515549177): Disabled linkinator globally due to broken external doc links.
-            task: "--rubocop-toplevel --rubocop --build --yard"
+            task: "--rubocop-toplevel --rubocop --build --yard --doctest"
           - os: macos-latest
             ruby: "4.0"
             task: "--test"
diff --git a/.toys/ci.rb b/.toys/ci.rb
index a1cd344821c7..266c92c025cd 100644
--- a/.toys/ci.rb
+++ b/.toys/ci.rb
@@ -19,14 +19,15 @@
   "rubocop",
   "build",
   "yard",
+  "doctest",
   "linkinator",
   "acceptance",
   "conformance",
   "samples-main",
   "samples-latest",
 ].freeze
-OPTIONAL_TASKS = ["conformance"].freeze
-ISSUE_TASKS = ["bundle", "test", "rubocop", "build", "yard", "linkinator"].freeze
+OPTIONAL_TASKS = ["conformance", "doctest"].freeze
+ISSUE_TASKS = ["bundle", "test", "rubocop", "build", "yard", "doctest", "linkinator"].freeze
 FAILURES_REPORT_PATH = "tmp/ci-failures.json"
 
 desc "Run CI tasks."